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Oval duct transition fitting STL 3D file 80x30 mm to 50x15 mm – transition: 40 mm

Enclosure with screw-mounted lid STL file: 100×100×20 mm (with ventilation on the lid and under the enclosure)

Pipe elbow STL file 30° ⌀OD: 60 mm ⌀ID: 58 mm thickness: 1 mm

Enclosure with screw-mounted lid STL 3D file: 120×100×45 mm (with ventilation on the lid)

Round air vent STL file ∅ 93.6 mm, slat angle: 30°

Small parts organizer with 6 drawers 20×15×30 mm STL file, thickness: 2 mm

Multi-tubes fitting 3 tubes STL 3D model – Outer diameter 50 mm, wall thickness 5 mm

Round-to-Rectangular Tube Adapter STL file ⌀100 mm to 50×50 mm, thickness 2 mm

Small parts organizer with 25 drawers 40×30×50 mm STL 3D file, thickness: 2 mm

Multi-compartment box STL 3D file: 14 compartments of 14×14×5 mm

Browse a growing library of free STL files and 3D models — or generate custom parts online to your exact specs.

Featured Model of the Day

Tube STL 3D file OD 26 mm, ID 23.5 mm, length 70 mm 📦 #5566

1 object(s) - format STL

View of object #0

Latest user-generated 3D models

Enclosure with screw-mounted lid STL 3D file: 103×77×230 mm 📦 #11621

2 object(s) - format STL

View of object #0

From the Blog

Why Modeling Strategy Matters in Procedural CAD Modeling

2025-12-14 · 3D Modeling · sylvain

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 #4481

2 object(s)

- format STL

Enclosure with screw-mounted lid STL 3D file: 300×40×20 mm (with ventilation on the lid and under the enclosure)

Download this enclosure with a screwed lid in 3D STL format. The dimensions are 300 mm long by 40 mm wide and 20 mm high. The lid only measures 10 mm high. Wall thickness is 2 mm. This enclosure features significant cooling area on the lid and under the base.

Parameter	Value	Unit
length	300	mm
width	40	mm
total height	20	mm
lid height	10	mm
wall thickness	2	mm
screw margin	0.1	mm
fit clearance	0.1	mm
cooling level	10
cooling zone(s)	cutouts on b...

📦 Model #4497

1 object(s)

- format STL

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 #2390

1 object(s)

- format STL

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 #4411

1 object(s)

- format STL

Multi-compartment box STL 3D file: 10 compartments of 50×50×100 mm

This 3D model in STL format provides 10 sections measuring 50×50×100mm each. The total dimensions of the box are 106×262×102mm. The compartments are not equipped with any fillet.

Parameter	Value	Unit
number of rows	5
number of columns	2
compartment length	50	mm
compartment width	50	mm
compartment height	100	mm
wall thickness	2	mm
compartment fillet (radius)	0	mm

📦 Model #954

1 object(s)

- format STL

U-shaped handle STL 3D file 50×100×20 mm (Center-to-center 80 mm)

Download this STL 3D model of a simple U-shaped furniture handle. The overall dimensions are 50×100×20 mm. The handle has a round profile combined with a right-angled transition. The mounting holes are 6 mm diameter and have a 80 mm center-to-center distance.

Parameter	Value	Unit
width	50	mm
length	100	mm
thickness	20	mm
shape (0:square,1:circle)	1
transition (0:right,1:rounded)	0
fillet radius	0	mm
hole diameter	6	mm

📦 Model #3610

1 object(s)

- format STL

O-ring STL file ID 11 × CS 4 mm

STL file of O-ring with dimensions Internal diameter 11 mm by section thickness 4 mm. Outer diameter (OD) resulting is 19 mm.

Parameter	Value	Unit
inner diameter (ID)	11	mm
cross section (CS)	4	mm

📦 Model #2520

1 object(s)

- format STL

L-bracket 150×110 mm STL 3D file, thickness 8 mm, hole diameter 6 mm

Model of a corner bracket reinforced in STL format. The dimensions are 150 mm in length, 110 mm in height, 50 mm in width, and 8 mm in thickness. The screw holes have a diameter of 6 mm. Chamfers are applied to the holes to improve the seating of the heads. The reinforcing bar enhances mechanical strength and includes two openings for fastening. This bracket prints without support, placed flat on the build plate.

Parameter	Value	Unit
length	150	mm
height	110	mm
width	50	mm
thickness	8	mm
hole diameter	6	mm
chamfer on the holes	yes

📦 Model #4145

1 object(s)

- format STL

Honeycomb grille STL file, 195x80mm, mesh: 7mm

Download this rectangular protective grid file in STL format. The overall size is 195x80 mm, with wide 7 mm cell size to enhance ventilation. This grid acts as a protective guard while allowing airflow.

Parameter	Value	Unit
length or center-to-center	195	mm
width or center-to-center	80	mm
mesh size	7	mm
dual color	no
holes	no

📦 Model #3057

1 object(s)

- format STL

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 #3612

1 object(s)

- format STL

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 #3523

1 object(s)

- format STL

Honeycomb grid STL 3D file, center-to-center: 110x110mm, mesh: 4mm - Ø4mm

Download this square honeycomb grid file in STL format. Mounting holes are placed at the four corners (center-to-center 110x110 mm), each with a diameter of Ø4 mm. The overall dimensions reach 118x118 mm, with standard 4 mm cell size for versatile use. This grid serves as both a protective guard and a ventilation panel.

Parameter	Value	Unit
length or center-to-center	110	mm
width or center-to-center	110	mm
mesh size	4	mm
dual color	no
holes	yes
hole diameter	4	mm

📦 Model #4475

1 object(s)

- format STL

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 #4396

1 object(s)

- format STL

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 #3943

1 object(s)

- format STL

Pipe elbow STL 3D file 90° ⌀OD: 32 mm ⌀ID: 12.5 mm thickness: 9.75 mm

3D model of a tubing elbow with a 90° angle in STL format. This pipe elbow has an external diameter of 32 mm and an internal diameter of 12.5 mm. The tube thickness is therefore 9.75 mm.

Parameter	Value	Unit
outer diameter	32	mm
inner diameter	12.5	mm
angle	90	°
end fillets	no

📦 Model #4414

2 object(s)

- format STL

Round box with lid STL 3D file ⌀ 134 mm - Height: 20 mm, Shell: 2 mm

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 #1483

1 object(s)

- format STL

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 #4201

1 object(s)

- format STL

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 #1843

1 object(s)

- format STL

Tube adapter STL file ⌀ 250–60 mm (Length: 80 mm)

Inline tube reducer ⌀250 mm to ⌀60 mm in STL format. Length of this reducer is 80 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a length of 20 mm, the smaller one of 20 mm as well. The ends are not rounded.

Parameter	Value	Unit
side A length	20	mm
side A outer diameter	250	mm
side A thickness	2	mm
side B length	20	mm
side B outer diameter	60	mm
side B thickness	2	mm
transition length	40	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #1215

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 86–81 mm (Length: 111 mm)

Inline tube coupler ⌀86 mm to ⌀81 mm in STL format. Total length of this reducer is 111 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a sleeve length of 46 mm, the smaller one of 45 mm. The ends are rounded on the outside to make tube connection easier.

Parameter	Value	Unit
side A length	46	mm
side A outer diameter	86	mm
side A thickness	3	mm
side B length	45	mm
side B outer diameter	81	mm
side B thickness	3	mm
transition length	20	mm
axis offset	0	mm
ends fillet	fillet on th...

📦 Model #1823

1 object(s)

- format STL

Tube adapter STL file ⌀ 88–25 mm (Length: 63 mm)

Tube coupler ⌀88 mm to ⌀25 mm in STL format. Total length of this adapter is 63 mm. The thickness of the tubes is identical: 4 mm. The larger-diameter tube has a length of 25 mm, the smaller one of 25 mm as well. The ends have no fillet.

Parameter	Value	Unit
side A length	25	mm
side A outer diameter	88	mm
side A thickness	4	mm
side B length	25	mm
side B outer diameter	25	mm
side B thickness	4	mm
transition length	13	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #3491

1 object(s)

- format STL

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 #6362

2 object(s)

- format STL

Rectangular-base box with lid STL 3D model – 84×45×20 mm, wall thickness 2 mm

Rectangular-base box with a lid provided as a STL 3D file. Overall dimensions are 84 mm long, 45 mm wide, and 20 mm tall. The box features thin 2 mm walls. Interior and exterior edges are rounded. A small clearance is included to ensure a precise fit between the box and the lid. The internal dimensions, excluding rounding, are 80 mm × 41 mm × 16 mm.

Parameter	Value	Unit
length	84	mm
width	45	mm
height	20	mm
wall thikness	2	mm

📦 Model #1075

1 object(s)

- format STL

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 #4476

1 object(s)

- format STL

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 #3502

1 object(s)

- format STL

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 #2101

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀100 mm to 172×15 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 inner dimensions 172×15 mm. The wall thickness is 2 mm and the total length is 180 mm. The adapter has an offset of 47.5 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	172	mm
rectangle internal height	15	mm
rectangle inlet length	30	mm
offset Z	47.5	mm
offset Y	0	mm
total length	180	mm
thickness	2	mm
chamfer	chamfers on ...

📦 Model #3962

1 object(s)

- format STL

Bowl STL 3D file, inner: base Ø120 mm, top Ø130 mm, height 40 mm - wall thickness 3 mm

Download this 3D model of a pot in STL format. This model can be used for storing small parts in a workshop or on a desk. The shape is open, with a internal height of 40 mm, a internal diameter at the top of 130 mm, and a internal diameter at the bottom of 120 mm. The wall is thickened. The total height is 43 mm.

Parameter	Value	Unit
inner bottom diameter	120	mm
inner top diameter	130	mm
inner height	40	mm
wall thickness	3	mm

📦 Model #3495

1 object(s)

- format STL

Honeycomb grid STL 3D file, center-to-center: 120x120mm, mesh: 5mm - Ø6mm

3D square protective honeycomb grid file in STL format. Mounting holes are placed at the four corners (center-to-center 120x120 mm), each with a diameter of Ø6 mm. The overall dimensions reach 132x132 mm, with standard 5 mm cell size for versatile use. This grid acts as a protective guard while allowing airflow.

Parameter	Value	Unit
length or center-to-center	120	mm
width or center-to-center	120	mm
mesh size	5	mm
dual color	no
holes	yes
hole diameter	6	mm

📦 Model #4503

1 object(s)

- format STL

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 #2064

2 object(s)

- format STL

Round box with lid STL 3D file ⌀ 35 mm - Height: 63 mm, Shell: 2 mm

Download this cylindrical box model in STL format. Its diameter is 35 mm and its height is 63 mm. The walls have a thickness of 2 mm. A large fillet located at the bottom of the box makes it easier to grip objects present inside.

Parameter	Value	Unit
external diameter	35	mm
total height	63	mm
wall thickness	2	mm
fit clearance	0.1	mm
inner bottom fillet	5	mm

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.