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Honeycomb grille STL file, center-to-center: 230x30mm, mesh: 8mm - Ø5mm

Shelf bracket 100×100 mm STL file, thickness 12 mm, hole diameter 6 mm

Round air vent STL file ∅ 90 mm, slat angle: 35°

Tube adapter STL 3D file ⌀ 100–16 mm (Length: 110 mm)

Square-base box with lid STL 3D model – 70×70×40 mm, wall thickness 4 mm

Oval hose adapter STL 3D file 140x40 mm to 130x35 mm – transition: 40 mm

Small parts organizer with 6 drawers 40×15×30 mm STL 3D file, thickness: 2 mm

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

4 ways fitting STL 3D file – Outer diameter 40 mm, wall thickness 3.75 mm

Round box with lid STL 3D file ⌀ 100 mm - Height: 20 mm, Shell: 3 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

Corner bracket 250×250 mm STL 3D file, thickness 8 mm, hole diameter 5 mm 📦 #2669

1 object(s) - format STL

View of object #0

Latest user-generated 3D models

Rectangular-base box with lid STL 3D file – 165×90×65 mm, wall thickness 2 mm 📦 #9570

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 #2833

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL file ⌀101.6 mm to 210.5×170.5 mm, thickness 3 mm + offset

File in STL format of a round-to-rectangular adapter with an outer diameter of ⌀101.6 mm and a rectangular section with inner dimensions 210.5×170.5 mm. The wall thickness is 3 mm and the overall length is 110 mm. The adapter has an offset of 14 mm along the Z axis. Chamfers are applied on the outside of the cylindrical end and on the inside of the rectangular end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	101.6	mm
cylinder inlet length	50	mm
rectangle internal length	210.5	mm
rectangle internal height	170.5	mm
rectangle inlet length	30	mm
offset Z	14	mm
offset Y	0	mm
total length	110	mm
thickness	3	mm
chamfer	chamfers on ...

📦 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 #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 #4421

1 object(s)

- format STL

Protective grid STL file, 300x270mm, mesh: 10mm

3D rectangular protective honeycomb grid model as a STL file. The overall size is 300x270 mm, with extra wide 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	300	mm
width or center-to-center	270	mm
mesh size	10	mm
dual color	no
holes	no

📦 Model #2614

1 object(s)

- format STL

Mounting bracket 200×200 mm STL file, thickness 8 mm, hole diameter 6 mm

3D file of a mounting bracket with a reinforcing bar in STL format. The dimensions are 200 mm in length, 200 mm in height, 50 mm in width, and 8 mm in thickness. The mounting holes are designed with a diameter of 6 mm. Chamfers are done to the holes to improve the seating of the heads. The reinforcing bar enhances mechanical strength and provides two openings for screwdriver access. No support is needed to print this bracket, printed flat on the build plate.

Parameter	Value	Unit
length	200	mm
height	200	mm
width	50	mm
thickness	8	mm
hole diameter	6	mm
chamfer on the holes	yes

📦 Model #2288

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 160–110 mm (Length: 65 mm)

Tube adapter ⌀160 mm to ⌀110 mm in STL 3D format. Total length of this fitting is 65 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a length of 30 mm, the smaller one of 30 mm as well. The ends are raw.

Parameter	Value	Unit
side A length	30	mm
side A outer diameter	160	mm
side A thickness	3	mm
side B length	30	mm
side B outer diameter	110	mm
side B thickness	3	mm
transition length	5	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #4088

2 object(s)

- format STL

Protective grid STL 3D file, 100x70mm, mesh: 3mm

Honeycomb rectangular grid model in STL format. The overall size is 100x70 mm, with fine 3 mm cell size for strong protection. A secondary color border highlights the perimeter. This type of grid serves both protection and ventilation roles.

Parameter	Value	Unit
length or center-to-center	100	mm
width or center-to-center	70	mm
mesh size	3	mm
dual color	yes
holes	no

📦 Model #3038

2 object(s)

- format STL

Honeycomb grid STL file, center-to-center: 210x140mm, mesh: 3mm - Ø4mm

Download this honeycomb protective rectangular grid as a STL file. Mounting holes are placed at the four corners (center-to-center 210x140 mm), each with a diameter of Ø4 mm. The overall dimensions reach 218x148 mm, with very fine 3 mm cell size for maximum protection. A secondary color frame emphasizes the border. 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	140	mm
mesh size	3	mm
dual color	yes
holes	yes
hole diameter	4	mm

📦 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 #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 #2466

1 object(s)

- format STL

Pipe elbow STL file 90° ⌀OD: 76 mm ⌀ID: 72 mm thickness: 2 mm

Model of a pipe elbow with a 90° angle in STL format. This pipe elbow features an external diameter of 76 mm and an internal diameter of 72 mm. The tube thickness is therefore 2 mm.

Parameter	Value	Unit
outer diameter	76	mm
inner diameter	72	mm
angle	90	°
end fillets	no

📦 Model #3921

1 object(s)

- format STL

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 #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 #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 #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 #2272

1 object(s)

- format STL

Multi-compartment box STL 3D file: 24 compartments of 40×40×20 mm

This compartment box design features 24 slots measuring 40×40×20mm each. The total dimensions are 261×175×23mm. Fillets of 3mm applied to all compartments help with item retrieval stored in the box. The dividers are particularly reinforced.

Parameter	Value	Unit
number of rows	4
number of columns	6
compartment length	40	mm
compartment width	40	mm
compartment height	20	mm
wall thickness	3	mm
compartment fillet (radius)	3	mm

📦 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 #1494

1 object(s)

- format STL

Pipe elbow STL 3D file 90° ⌀OD: 50 mm ⌀ID: 44 mm thickness: 3 mm

3D model of a pipe elbow with a 90° angle in STL format. This pipe elbow features an external diameter of 50 mm and an internal diameter of 44 mm. This results in a tube thickness of 3 mm. End fillets make it easier to assemble.

Parameter	Value	Unit
outer diameter	50	mm
inner diameter	44	mm
angle	90	°
end fillets	yes

📦 Model #1216

1 object(s)

- format STL

O-ring STL file ID 18 × CS 4.6 mm

File of O-ring (torus-shaped seal) with dimensions Inner diameter 18 mm by CS (cross section) 4.6 mm. The outer diameter is 27.2 mm.

Parameter	Value	Unit
inner diameter (ID)	18	mm
cross section (CS)	4.6	mm

📦 Model #3133

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 86–75 mm (Length: 160 mm)

Straight tubing adapter ⌀86 mm to ⌀75 mm in STL format. Final length of this junction is 160 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a sleeve length of 70 mm, the smaller one of 60 mm. The ends have no fillet.

Parameter	Value	Unit
side A length	70	mm
side A outer diameter	86	mm
side A thickness	3	mm
side B length	60	mm
side B outer diameter	75	mm
side B thickness	3	mm
transition length	30	mm
axis offset	0	mm
ends fillet	no fillet

📦 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 #1333

1 object(s)

- format STL

Round air vent STL file ∅ 120 mm, slat angle: 45° with central reinforcement

3D file of a round vent cover for air circulation in STL format. Its male diameter measures 120 mm. The slats have an angle of 45° and a low thickness of 1.6 mm. A vertical reinforcement strengthens the slats. This 3D vent cover has a thin flange of 5 mm. The overall diameter of the model is 130 mm.

Parameter	Value	Unit
male diameter	120	mm
slat angle	45	°
slat thickness	1.6	mm
flange width	5	mm
central reinforcement	yes

📦 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 #1872

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL file ⌀105 mm to 150×50 mm, thickness 3 mm + offset

File in STL format of a round-to-rectangular adapter with an external diameter of ⌀105 mm and a rectangular section with inner dimensions 150×50 mm. The shell thickness is 3 mm and the overall length is 100 mm. The adapter has an offset of 10 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	105	mm
cylinder inlet length	30	mm
rectangle internal length	150	mm
rectangle internal height	50	mm
rectangle inlet length	50	mm
offset Z	10	mm
offset Y	0	mm
total length	100	mm
thickness	3	mm
chamfer	no chamfer

📦 Model #2941

2 object(s)

- format STL

Small parts organizer with 1 drawer 150×150×150 mm STL file, thickness: 2 mm

Download this file of a storage organizer in STL format. This model includes 1 drawer, arranged in 1 rows and 1 columns. Specifically, this means 1 rows of 1 drawers. Each drawer provides an inside space of 150 mm wide, 150 mm high, and 150 mm deep. The wall thickness is 2 mm. The total size of the structure come to 158.5 x 156.5 x 156 mm. All the objects in this model are intended to be printed without support generation.

Parameter	Value	Unit
number of rows	1
number of columns	1
inner drawer depth	150	mm
inner drawer width	150	mm
inner drawer height	150	mm
wall thickness	2	mm
removable divider	none

📦 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 #4459

1 object(s)

- format STL

Honeycomb grille STL file, center-to-center: 245x245mm, mesh: 8mm - Ø4mm

3D square protective honeycomb grid model in STL format. Mounting holes are placed at the four corners (center-to-center 245x245 mm), each with a diameter of Ø4 mm. The overall dimensions reach 253x253 mm, with large 8 mm cell size to maximize airflow. This grid functions as both a mechanical guard and a ventilation panel.

Parameter	Value	Unit
length or center-to-center	245	mm
width or center-to-center	245	mm
mesh size	8	mm
dual color	no
holes	yes
hole diameter	4	mm

📦 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 #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 #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...

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.