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Featured Model of the Day

Oval duct transition fitting STL file 100.1x100 mm to 80x40 mm – transition: 20 mm 📦 #4342

1 object(s) - format STL

gizmo

Latest user-generated 3D models

Tubing adapter STL file ⌀ 79–36 mm (Length: 180 mm) 📦 #9434

1 object(s) - format STL

gizmo

From the Blog

Why Modeling Strategy Matters in Procedural CAD Modeling

2025-12-14 · 3D Modeling · sylvain
why Modeling Strategy Matters in Procedural CAD Modeling why Modeling Strategy Matters in Procedural CAD Modeling

Why does modeling strategy matter so much in procedural CAD? Two scripts can produce the exact same geometry while showing very different generation times.

Using a concrete build123d example, this article explains why certain operations, such as fillets, become expensive when repeated at scale, and how a simple change in approach can drastically reduce computation time.

A clear overview of the key challenges in procedural modeling, highlighting the direct impact of design choices on CAD engine performance.

Read the article

A selection of custom 3D models

📦 Model #2390

1 object(s)
- format STL
Round air vent STL 3D file ∅ 115 mm, slat angle: 45°
Round air vent STL 3D file ∅ 115 mm, slat angle: 45°
3D file of a round grille for air circulation in STL format. Its male diameter is 115 mm. The slats have an angle of 45° and a high thickness of 2 mm. This ventilation grille has a collar of 10 mm. The full diameter of this model is 135 mm.
Parameter Value Unit
male diameter 115 mm
slat angle 45 °
slat thickness 2 mm
flange width 10 mm
central reinforcement no

📦 Model #3612

1 object(s)
- format STL
Protective grid STL 3D file, center-to-center: 210x110mm, mesh: 10mm - Ø5mm
Protective grid STL 3D file, center-to-center: 210x110mm, mesh: 10mm - Ø5mm
Download this rectangular protective honeycomb grid model in STL format. Mounting holes are placed at the four corners (center-to-center 210x110 mm), each with a diameter of Ø5 mm. The overall dimensions reach 220x120 mm, with very large 10 mm cell size for peak ventilation. This grid serves as both a protective guard and a ventilation panel.
Parameter Value Unit
length or center-to-center 210 mm
width or center-to-center 110 mm
mesh size 10 mm
dual color no
holes yes
hole diameter 5 mm

📦 Model #992

1 object(s)
- format STL
U-shaped handle STL 3D file 50×140×14 mm (Center-to-center 126 mm)
U-shaped handle STL 3D file 50×140×14 mm (Center-to-center 126 mm)
Download this STL 3D file of a U-shaped handle. The overall dimensions are 50×140×14 mm. This handle has a round profile combined with a rounded transition. The bores are 5 mm diameter with a center-to-center distance of 126 mm.
Parameter Value Unit
width 50 mm
length 140 mm
thickness 14 mm
shape (0:square,1:circle) 1
transition (0:right,1:rounded) 1
fillet radius 0 mm
hole diameter 5 mm

📦 Model #3491

1 object(s)
- format STL
Protective grid STL file, center-to-center: 107x107mm, mesh: 10mm - Ø5mm
Protective grid STL file, center-to-center: 107x107mm, mesh: 10mm - Ø5mm
3D square protective honeycomb grid model as a STL file. Mounting holes are placed at the four corners (center-to-center 107x107 mm), each with a diameter of Ø5 mm. The overall dimensions reach 117x117 mm, with very large 10 mm cell size for maximum airflow. This grid serves as both a protective guard and a ventilation panel.
Parameter Value Unit
length or center-to-center 107 mm
width or center-to-center 107 mm
mesh size 10 mm
dual color no
holes yes
hole diameter 5 mm

📦 Model #4476

1 object(s)
- format STL
Tubing adapter STL 3D file ⌀ 40–37 mm (Length: 115 mm)
Tubing adapter STL 3D file ⌀ 40–37 mm (Length: 115 mm)
Tube adapter ⌀40 mm to ⌀37 mm in STL 3D format. Length of this connector is 115 mm. The thickness of the tubes is identical: 5 mm. The larger-diameter tube has a sleeve length of 35 mm, the smaller one of 40 mm. The ends are rounded to facilitate the connection of the two tubes.
Parameter Value Unit
side A length 35 mm
side A outer diameter 40 mm
side A thickness 5 mm
side B length 40 mm
side B outer diameter 37 mm
side B thickness 5 mm
transition length 40 mm
axis offset 0 mm
ends fillet fillet on bo...

📦 Model #2049

2 object(s)
- format STL
Small parts organizer with 1 drawer 89×89×89 mm STL 3D file, thickness: 3 mm
Small parts organizer with 1 drawer 89×89×89 mm STL 3D file, thickness: 3 mm
View of object #0
Download this model of a sorting cabinet with drawers in STL format. This model contains 1 box, arranged in 1 rows and 1 columns. Specifically, this means 1 rows of 1 boxes. Each box offers a storage volume of 89 mm wide, 89 mm high, and 89 mm deep. The wall thickness is 3 mm, which makes the structure sturdy. The total size of the structure measure 101.5 x 98.5 x 98 mm. All the objects in this model were designed to be printed without support generation.
Parameter Value Unit
number of rows 1
number of columns 1
inner drawer depth 89 mm
inner drawer width 89 mm
inner drawer height 89 mm
wall thickness 3 mm
removable divider none

📦 Model #784

1 object(s)
- format STL
Rectangular prism STL file 80×82×30 mm
Rectangular prism STL file 80×82×30 mm
Download this 3D model of a box as an STL file. The final dimensions are 80×82×30 mm. A small fillet softens all the sides.
Parameter Value Unit
length 80 mm
width 82 mm
height 30 mm
fillet radius 2 mm

📦 Model #1550

1 object(s)
- format STL
Tube adapter STL 3D file ⌀ 111–90 mm (Length: 170 mm)
Tube adapter STL 3D file ⌀ 111–90 mm (Length: 170 mm)
Tube connector ⌀111 mm to ⌀90 mm in STL format. Final length of this adapter is 170 mm. The thickness of the tubes is identical: 5 mm. The larger-diameter tube has a sleeve length of 70 mm, the smaller one of 80 mm. The ends have a fillet on the outside to ease the connection.
Parameter Value Unit
side A length 70 mm
side A outer diameter 111 mm
side A thickness 5 mm
side B length 80 mm
side B outer diameter 90 mm
side B thickness 5 mm
transition length 20 mm
axis offset 0 mm
ends fillet fillet on th...

📦 Model #4396

1 object(s)
- format STL
Honeycomb grid STL file, 250x250mm, mesh: 10mm
Honeycomb grid STL file, 250x250mm, mesh: 10mm
Square grid model as a STL file. The overall size is 250x250 mm, with very large 10 mm cell size for maximum airflow. This grid serves as both a protective guard and a ventilation panel.
Parameter Value Unit
length or center-to-center 250 mm
width or center-to-center 250 mm
mesh size 10 mm
dual color no
holes no

📦 Model #3890

1 object(s)
- format STL
Right-angle bracket 150×100 mm STL file, thickness 12 mm, hole diameter 5 mm
Right-angle bracket 150×100 mm STL file, thickness 12 mm, hole diameter 5 mm
3D file of a corner bracket reinforced in STL format. The dimensions are 150 mm in length, 100 mm in height, 20 mm in width, and 12 mm in thickness. The holes have a diameter of 5 mm. Chamfers are done to the holes to seat the screw heads. The reinforcing bar enhances mechanical strength and provides two openings for screwdriver access. This bracket prints without support, placed flat directly on the build plate.
Parameter Value Unit
length 150 mm
height 100 mm
width 20 mm
thickness 12 mm
hole diameter 5 mm
chamfer on the holes yes

📦 Model #4503

1 object(s)
- format STL
Tube adapter STL 3D file ⌀ 125–80 mm (Length: 105 mm)
Tube adapter STL 3D file ⌀ 125–80 mm (Length: 105 mm)
Straight tube coupler ⌀125 mm to ⌀80 mm in STL format. Total length of this junction is 105 mm. The thickness of the tubes is identical: 5 mm. The larger-diameter tube has a sleeve length of 35 mm, the smaller one of 40 mm. The ends are raw.
Parameter Value Unit
side A length 35 mm
side A outer diameter 125 mm
side A thickness 5 mm
side B length 40 mm
side B outer diameter 80 mm
side B thickness 5 mm
transition length 30 mm
axis offset 0 mm
ends fillet no fillet

📦 Model #2103

1 object(s)
- format STL
Round-to-Rectangular Tube Adapter STL file ⌀126.0 mm to 145.0×69.5 mm, thickness 3 mm + offset
Round-to-Rectangular Tube Adapter STL file ⌀126.0 mm to 145.0×69.5 mm, thickness 3 mm + offset
Download this 3D model in STL format of a round-to-rectangular adapter with an outer diameter of ⌀126.0 mm and a rectangular section with internal dimensions 145.0×69.5 mm. The shell thickness is 3 mm and the overall length is 64.5 mm. The adapter has an offset of 16.7 mm along the Z axis.
Parameter Value Unit
cylinder outer diameter 126.0 mm
cylinder inlet length 20 mm
rectangle internal length 145.0 mm
rectangle internal height 69.5 mm
rectangle inlet length 11 mm
offset Z 16.7 mm
offset Y 0 mm
total length 64.5 mm
thickness 3 mm
chamfer no chamfer

📦 Model #4418

1 object(s)
- format STL
Round-to-Rectangular Tube Adapter STL 3D file ⌀100 mm to 200×30 mm, thickness 2 mm + offset
Round-to-Rectangular Tube Adapter STL 3D file ⌀100 mm to 200×30 mm, thickness 2 mm + offset
3D file in STL format of a round-to-rectangular adapter with an external diameter of ⌀100 mm and a rectangular section with internal dimensions 200×30 mm. The shell thickness is 2 mm and the total length is 80 mm. The adapter has an offset of 15 mm along the Y axis and 15 mm along the Z axis. Chamfers are present on the outside of the cylindrical end and on the inside of the rectangular end.
Parameter Value Unit
cylinder outer diameter 100 mm
cylinder inlet length 30 mm
rectangle internal length 200 mm
rectangle internal height 30 mm
rectangle inlet length 20 mm
offset Z 15 mm
offset Y 15 mm
total length 80 mm
thickness 2 mm
chamfer chamfers on ...

📦 Model #2198

1 object(s)
- format STL
Round-to-Rectangular Tube Adapter STL file ⌀40 mm to 68×24 mm, thickness 3 mm
Round-to-Rectangular Tube Adapter STL file ⌀40 mm to 68×24 mm, thickness 3 mm
3D model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀40 mm and a rectangular section with internal dimensions 68×24 mm. The shell thickness is 3 mm and the total length is 100 mm. Chamfers are present on the outside of the cylindrical end and on the inside of the rectangular end.
Parameter Value Unit
cylinder outer diameter 40 mm
cylinder inlet length 40 mm
rectangle internal length 68 mm
rectangle internal height 24 mm
rectangle inlet length 40 mm
offset Z 0 mm
offset Y 0 mm
total length 100 mm
thickness 3 mm
chamfer chamfers on ...

📦 Model #2384

1 object(s)
- format STL
Round air vent STL file ∅ 80 mm, slat angle: 45° with central reinforcement
Round air vent STL file ∅ 80 mm, slat angle: 45° with central reinforcement
File of a round air vent for ventilation in STL format. Its male diameter is 80 mm. The slats have an angle of 45° and a high thickness of 2 mm. A vertical reinforcement reinforces the whole structure. This 3D vent grille features a prominent flange of 20 mm. The overall diameter of the model is 120 mm.
Parameter Value Unit
male diameter 80 mm
slat angle 45 °
slat thickness 2 mm
flange width 20 mm
central reinforcement yes

📦 Model #1483

1 object(s)
- format STL
Tube adapter STL file ⌀ 200–50 mm (Length: 80 mm)
Tube adapter STL file ⌀ 200–50 mm (Length: 80 mm)
Tube reducer ⌀200 mm to ⌀50 mm in STL 3D format. Total length of this junction is 80 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a sleeve length of 30 mm, the smaller one of 30 mm as well. The ends have no fillet.
Parameter Value Unit
side A length 30 mm
side A outer diameter 200 mm
side A thickness 3 mm
side B length 30 mm
side B outer diameter 50 mm
side B thickness 3 mm
transition length 20 mm
axis offset 0 mm
ends fillet no fillet

📦 Model #755

1 object(s)
- format STL
Rectangular prism STL 3D file 100×70×29 mm
Rectangular prism STL 3D file 100×70×29 mm
Download a rectangular prism as a 3D STL file. Its final dimensions are 100×70×29 mm. No fillet is present on the model.
Parameter Value Unit
length 100 mm
width 70 mm
height 29 mm
fillet radius 0 mm

📦 Model #4447

1 object(s)
- format STL
Tube adapter STL 3D file ⌀ 100–79 mm (Length: 240 mm)
Tube adapter STL 3D file ⌀ 100–79 mm (Length: 240 mm)
Straight tube fitting ⌀100 mm to ⌀79 mm in STL 3D format. Total length of this sleeve is 240 mm. The larger-diameter tube has a thickness of 4 mm and a sleeve length of 100 mm. The smaller-diameter tube has a thickness of 5 mm and a length of 100 mm as well. The axes of the tubes are offset by 11.4 mm. The ends feature an external fillet.
Parameter Value Unit
side A length 100 mm
side A outer diameter 100 mm
side A thickness 4 mm
side B length 100 mm
side B outer diameter 79 mm
side B thickness 5 mm
transition length 40 mm
axis offset 11.4 mm
ends fillet fillet on th...

📦 Model #4475

1 object(s)
- format STL
Tube adapter STL 3D file ⌀ 40–37 mm (Length: 118 mm)
Tube adapter STL 3D file ⌀ 40–37 mm (Length: 118 mm)
Straight tube fitting ⌀40 mm to ⌀37 mm in STL format. Total length of this connector is 118 mm. The thickness of the tubes is identical: 5 mm. The larger-diameter tube has a sleeve length of 38 mm, the smaller one of 40 mm. The ends have a fillet to make tube connection easier.
Parameter Value Unit
side A length 38 mm
side A outer diameter 40 mm
side A thickness 5 mm
side B length 40 mm
side B outer diameter 37 mm
side B thickness 5 mm
transition length 40 mm
axis offset 0 mm
ends fillet fillet on bo...

📦 Model #3502

1 object(s)
- format STL
Protective grid STL 3D file, 60x60mm, mesh: 8mm
Protective grid STL 3D file, 60x60mm, mesh: 8mm
Download this 3D square honeycomb grid model in STL format. The overall size is 60x60 mm, with wide 8 mm cell size for optimal air circulation. This type of grid serves both protection and ventilation roles.
Parameter Value Unit
length or center-to-center 60 mm
width or center-to-center 60 mm
mesh size 8 mm
dual color no
holes no

📦 Model #4326

1 object(s)
- format STL
Hose-shaped reducer STL 3D file 220x100 mm to 185x55 mm – transition: 20 mm
Hose-shaped reducer STL 3D file 220x100 mm to 185x55 mm – transition: 20 mm
Oval duct adapter in STL 3D file format. The internal cross-section on side A is 220x100 mm, while on side B it is 185x55 mm. A uniform useful length of 5 mm is available on both sleeves. The transition links the two ends over 20 mm, with a total overall length of 30 mm. With 1 mm of thickness, the wall remains flexible and material-efficient. The external edges at the ends are chamfered, which simplifies inserting the adapter into the duct. Side B is offset by 9 mm along the Y axis and 9 mm along the Z axis relative to side A.
Parameter Value Unit
side A internal width 220 mm
side A internal height 100 mm
sleeve length on side A 5 mm
side B internal width 185 mm
side B internal height 55 mm
sleeve length on side B 5 mm
thickness 1 mm
transition length 20 mm
Y offset 9 mm
Z offset 9 mm
end chamfers outside

📦 Model #4201

1 object(s)
- format STL
Washer / Flat Gasket STL 3D file ⌀ID: 3.9 mm ⌀OD: 6.9 mm thickness: 4.3 mm
Washer / Flat Gasket STL 3D file ⌀ID: 3.9 mm ⌀OD: 6.9 mm thickness: 4.3 mm
3D model of washer / gasket in STL 3D file format. This part features an inner diameter of ⌀3.9 mm and an outer diameter of ⌀6.9 mm. The total thickness is 4.3 mm. This part has no finish applied.
Parameter Value Unit
inner diameter 3.9 mm
outer diameter 6.9 mm
thickness 4.3 mm
finish none

📦 Model #1075

1 object(s)
- format STL
Multi-compartment box STL file: 12 compartments of 15.5×15.5×30 mm
Multi-compartment box STL file: 12 compartments of 15.5×15.5×30 mm
This printable multi-compartment box features 12 slots measuring 15.5×15.5×30mm each. The total dimensions of the box are 107×37×32mm. The slots do not feature any fillet.
Parameter Value Unit
number of rows 2
number of columns 6
compartment length 15.5 mm
compartment width 15.5 mm
compartment height 30 mm
wall thickness 2 mm
compartment fillet (radius) 0 mm

📦 Model #3057

1 object(s)
- format STL
Right-angle bracket 150×150 mm STL 3D file, thickness 6 mm, hole diameter 6 mm
Right-angle bracket 150×150 mm STL 3D file, thickness 6 mm, hole diameter 6 mm
3D file of a mounting bracket with a central reinforcement in STL format. The dimensions are 150 mm in length, 150 mm in height, 14 mm in width, and 6 mm in thickness. The screw holes are designed with a diameter of 6 mm. Chamfers are applied to the holes to improve the seating of the heads. The central reinforcement bar reduces bending and provides two clearances for screwdriver access. No support is needed to print this bracket, printed flat on the build plate.
Parameter Value Unit
length 150 mm
height 150 mm
width 14 mm
thickness 6 mm
hole diameter 6 mm
chamfer on the holes yes

📦 Model #4414

2 object(s)
- format STL
Round box with lid STL 3D file ⌀ 134 mm - Height: 20 mm, Shell: 2 mm
Round box with lid STL 3D file ⌀ 134 mm - Height: 20 mm, Shell: 2 mm
View of object #0
Get this circular box model in 3D STL format. Its diameter is 134 mm and its total height is 20 mm. The wall thickness is 2 mm. A fillet located at the bottom of the box makes it easier to grip objects.
Parameter Value Unit
external diameter 134 mm
total height 20 mm
wall thickness 2 mm
fit clearance 0.2 mm
inner bottom fillet 1 mm

📦 Model #1037

1 object(s)
- format STL
O-ring STL file ID 4.47 × CS 1.78 mm
O-ring STL file ID 4.47 × CS 1.78 mm
File of circular seal with dimensions ID (inner diameter) 4.47 mm × section thickness 1.78  mm. Final diameter is therefore 8.03 mm.
Parameter Value Unit
inner diameter (ID) 4.47 mm
cross section (CS) 1.78 mm

📦 Model #3987

2 object(s)
- format STL
Enclosure with screw-mounted lid STL file: 90×70×45 mm
Enclosure with screw-mounted lid STL file: 90×70×45 mm
View of object #0
Enclosure model with lid in STL format. The dimensions are 90 mm long by 70 mm wide and 45 mm high. The lid measures 17 mm high. Side thickness is 3 mm. The enclosure does not have cooling.
Parameter Value Unit
length 90 mm
width 70 mm
total height 45 mm
lid height 17 mm
wall thickness 3 mm
screw margin 0 mm
fit clearance 0.1 mm
cooling zone(s) no cutouts

📦 Model #4497

1 object(s)
- format STL
Tubing adapter STL 3D file ⌀ 32–19 mm (Length: 65 mm)
Tubing adapter STL 3D file ⌀ 32–19 mm (Length: 65 mm)
Tube fitting ⌀32 mm to ⌀19 mm in STL 3D format. Length of this junction is 65 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a sleeve length of 35 mm, the smaller one of 20 mm. The ends are not rounded.
Parameter Value Unit
side A length 35 mm
side A outer diameter 32 mm
side A thickness 2 mm
side B length 20 mm
side B outer diameter 19 mm
side B thickness 2 mm
transition length 10 mm
axis offset 0 mm
ends fillet no fillet

📦 Model #3921

1 object(s)
- format STL
Round air vent STL 3D file ∅ 93 mm, slat angle: 45° with central reinforcement
Round air vent STL 3D file ∅ 93 mm, slat angle: 45° with central reinforcement
File of a round grille for air circulation in STL format. Its insertion diameter is 93 mm. The slats have an angle of 45° and a high thickness of 2 mm. A centered vertical reinforcement strengthens the whole structure. This 3D vent cover has a thin flange of 4 mm. The full diameter of this model is 101 mm.
Parameter Value Unit
male diameter 93 mm
slat angle 45 °
slat thickness 2 mm
flange width 4 mm
central reinforcement yes

📦 Model #3179

1 object(s)
- format STL
Tube adapter STL 3D file ⌀ 50–46 mm (Length: 90 mm)
Tube adapter STL 3D file ⌀ 50–46 mm (Length: 90 mm)
Diameter adapter ⌀50 mm to ⌀46 mm in STL format. Final length of this coupler is 90 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a length of 30 mm, the smaller one of 35 mm. The ends are not rounded.
Parameter Value Unit
side A length 30 mm
side A outer diameter 50 mm
side A thickness 2 mm
side B length 35 mm
side B outer diameter 46 mm
side B thickness 2 mm
transition length 25 mm
axis offset 0 mm
ends fillet no fillet

STL: Advantages and Disadvantages for 3D Printing

The STL format is, without question, a cornerstone of 3D printing. This exchange format has established itself as the universal standard for representing 3D models ever since the early days of stereolithography. Its main strength lies in its simplicity: it describes the surface of an object using countless small triangles that form a mesh. This approach, known as tessellation, makes STL 3D files universally compatible with nearly all CAD software and slicers. If you’d like to learn more about this format, check out our article STL: What Is This 3D File Format?.

One of the major advantages of the format lies in this universality: whether you’re using a complex modeling program or a simpler design tool, you can export your 3D models in STL 3D format with near certainty that they’ll be interpreted correctly by your 3D printer. This ease of exchange has played a key role in the widespread adoption of 3D printing, allowing anyone to share and print objects without worrying about software compatibility. Once again, simplicity is its greatest strength.

However, that same simplicity also brings certain limitations. The triangle mesh, while effective for describing geometry, contains no information about colors, textures, or materials. For more advanced projects requiring these details, the STL format starts to show its weaknesses. Additionally, print quality depends directly on the fineness of the tessellation: too few triangles can lead to rough or faceted surfaces, while an overly dense mesh can make the file unnecessarily heavy.

Another notable drawback is the lack of unit management. An STL file doesn’t specify whether dimensions are in millimeters, centimeters, or inches, which can sometimes cause scaling errors when importing into a slicer. Despite these limitations, the STL format remains the go-to standard for converting your 3D models into G-code — the language your printer understands. It continues to be the preferred choice for its robustness and broad compatibility, even as newer formats like 3MF emerge for more specialized needs.

What is parametric modeling?

Parametric modeling is a fundamental approach in computer-aided design (CAD) that reshapes how 3D models are created and managed. Far from being a simple drawing technique, it represents a genuine design philosophy where objects are defined not by fixed shapes, but by variables and intelligent relationships.

This method makes it possible to modify the length, width, or diameter of a part and have the entire design adapt automatically, without the need to redraw everything. At the core of the process are parameters—numerical values (length, angle, thickness, etc.)—linked together through constraints and formulas. For instance, the diameter of a hole can be defined as half the width of a plate; if the width changes, the hole’s diameter instantly adjusts, ensuring the consistency of the design. This interdependence makes 3D models flexible and responsive to changes. One of the main advantages of parametric modeling lies in its ability to simplify customization and enable rapid iteration of designs.

Whether through modeling software such as Fusion 360 or FreeCAD, or through code-based libraries like build123d, this approach allows effortless exploration of a wide range of variations. Such flexibility is especially valuable across multiple fields—from mechanical engineering and architecture to consumer product design. It saves considerable time, reduces errors, and improves the performance of parts.

By defining design intent from the start through these parameters and constraints, the model preserves its integrity and functionality even after numerous modifications. It is a powerful way to transform an idea into a tangible object, ready to adapt to new situations.