Free custom STL files and 3D models for 3D printers

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Round air vent STL file ∅ 300 mm, slat angle: 30° with central reinforcement

Pot STL file, inner: base Ø40 mm, top Ø80 mm, height 50 mm - wall thickness 3 mm

Round-to-Rectangular Tube Adapter STL file ⌀60 mm to 50×10 mm, thickness 2 mm + offset

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

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

Rectangular tube adapter STL file 100x40 mm to 80x80 mm – transition: 80 mm

L-bracket 120×250 mm STL file, thickness 12 mm, hole diameter 6 mm

Pipe elbow STL 3D file 10° ⌀OD: 40 mm ⌀ID: 34 mm thickness: 3 mm

Tube adapter STL 3D file ⌀ 80–50 mm (Length: 80 mm)

Pipe elbow STL 3D file 180° ⌀OD: 18 mm ⌀ID: 16 mm thickness: 1 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

Rectangular prism STL file 100×44×55 mm 📦 #767

1 object(s) - format STL

Latest user-generated 3D models

Tube adapter STL 3D file ⌀ 61–41 mm (Length: 31 mm) 📦 #10163

1 object(s) - format STL

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 #2121

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL file ⌀126 mm to 139×63.5 mm, thickness 3 mm + offset

Download this 3D model in STL format of a round-to-rectangular adapter with an external diameter of ⌀126 mm and a rectangular section with internal dimensions 139×63.5 mm. The wall thickness is 3 mm and the total length is 150 mm. The adapter has an offset of 3 mm along the Y axis and 3 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	126	mm
cylinder inlet length	30	mm
rectangle internal length	139	mm
rectangle internal height	63.5	mm
rectangle inlet length	80	mm
offset Z	3	mm
offset Y	3	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

📦 Model #2131

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀250 mm to 250×150 mm, thickness 3 mm + offset

File in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀250 mm and a rectangular section with internal dimensions 250×150 mm. The shell thickness is 3 mm and the total length is 165 mm. The adapter has an offset of 15 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	250	mm
cylinder inlet length	50	mm
rectangle internal length	250	mm
rectangle internal height	150	mm
rectangle inlet length	80	mm
offset Z	15	mm
offset Y	0	mm
total length	165	mm
thickness	3	mm
chamfer	chamfers on ...

📦 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 #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 #2791

1 object(s)

- format STL

Tubing adapter STL 3D file ⌀ 64–32 mm (Length: 80 mm)

Inline tubing adapter ⌀64 mm to ⌀32 mm in STL 3D format. Total length of this reducer 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 a fillet on the inside to ease the connection.

Parameter	Value	Unit
side A length	30	mm
side A outer diameter	64	mm
side A thickness	3	mm
side B length	30	mm
side B outer diameter	32	mm
side B thickness	3	mm
transition length	20	mm
axis offset	0	mm
ends fillet	fillet on th...

📦 Model #3129

2 object(s)

- format STL

Small parts organizer with 3 drawers 100×50×100 mm STL 3D file, thickness: 3 mm

Model of a drawer organizer in STL format. This model includes 3 drawers, arranged in 1 rows and 3 columns. Practically speaking, this means 1 rows of 3 drawers. Each drawer offers a storage volume of 100 mm wide, 50 mm high, and 100 mm deep. The wall thickness is 3 mm, which makes the structure solid. The overall dimensions of the box are 331.5 x 59.5 x 109 mm. All the objects in this model are intended to be printable without support.

Parameter	Value	Unit
number of rows	1
number of columns	3
inner drawer depth	100	mm
inner drawer width	100	mm
inner drawer height	50	mm
wall thickness	3	mm
removable divider	none

📦 Model #1955

1 object(s)

- format STL

Round air vent STL file ∅ 100 mm, slat angle: 45° with central reinforcement

Design of a round air vent for air circulation in STL format. Its insertion diameter measures 100 mm. The slats have an angle of 45° and a high thickness of 2 mm. A vertical reinforcement secures the whole structure. This vent cover has a collar of 10 mm. The overall diameter of this model is 120 mm.

Parameter	Value	Unit
male diameter	100	mm
slat angle	45	°
slat thickness	2	mm
flange width	10	mm
central reinforcement	yes

📦 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 #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 #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 #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 #4242

2 object(s)

- format STL

Small parts organizer with 400 drawers 150×150×150 mm STL 3D file, thickness: 4 mm

File of a sorting cabinet with drawers in 3D STL format. This model features 400 boxes, arranged in 20 rows and 20 columns. Practically speaking, this means 20 rows of 20 boxes. Each box comes with an inner space of 150 mm wide, 150 mm high, and 150 mm deep. The wall thickness is 4 mm, which makes the structure very sturdy. The overall dimensions of the structure come to 3254 x 3174 x 162 mm. All the objects in this model are intended to be printable without support generation.

Parameter	Value	Unit
number of rows	20
number of columns	20
inner drawer depth	150	mm
inner drawer width	150	mm
inner drawer height	150	mm
wall thickness	4	mm
removable divider	none

📦 Model #1111

2 object(s)

- format STL

Round box with lid STL file ⌀ 50 mm - Height: 45 mm, Shell: 2 mm

Get this cylindrical organizing box in STL format. Its diameter is 50 mm and its total height is 45 mm. The wall thickness is 2 mm.

Parameter	Value	Unit
external diameter	50	mm
total height	45	mm
wall thickness	2	mm
fit clearance	0.1	mm
inner bottom fillet	0	mm

📦 Model #4175

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 15–12 mm (Length: 25 mm)

Inline tube reducer ⌀15 mm to ⌀12 mm in STL 3D format. Length of this coupler is 25 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a sleeve length of 10 mm, the smaller one of 10 mm as well. The ends are raw.

Parameter	Value	Unit
side A length	10	mm
side A outer diameter	15	mm
side A thickness	2	mm
side B length	10	mm
side B outer diameter	12	mm
side B thickness	2	mm
transition length	5	mm
axis offset	0	mm
ends fillet	no fillet

📦 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 #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 #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 #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 #3724

1 object(s)

- format STL

Protective grid STL 3D file, center-to-center: 300x106mm, mesh: 10mm - Ø6mm

Download this 3D honeycomb protective rectangular grid model in STL format. Mounting holes are placed at the four corners (center-to-center 300x106 mm), each with a diameter of Ø6 mm. The overall dimensions reach 312x118 mm, with very large 10 mm cell size for maximum airflow. This grid functions as both a mechanical guard and a ventilation panel.

Parameter	Value	Unit
length or center-to-center	300	mm
width or center-to-center	106	mm
mesh size	10	mm
dual color	no
holes	yes
hole diameter	6	mm

📦 Model #3390

1 object(s)

- format STL

Protective grid STL file, center-to-center: 104x104mm, mesh: 10mm - Ø4mm

Honeycomb protective square grid file in STL format. Mounting holes are placed at the four corners (center-to-center 104x104 mm), each with a diameter of Ø4 mm. The overall dimensions reach 112x112 mm, with very open 10 mm cell size for peak ventilation. This type of grid serves both protection and ventilation roles.

Parameter	Value	Unit
length or center-to-center	104	mm
width or center-to-center	104	mm
mesh size	10	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 #2310

2 object(s)

- format STL

Enclosure with screw-mounted lid STL file: 90×50×35 mm (with ventilation on the lid)

Download this enclosure with a screwed lid in STL format. The dimensions are 90 mm long by 50 mm wide and 35 mm high. The cover only is 15 mm high. Wall thickness is 3 mm. This enclosure features strong cooling area on the lid.

Parameter	Value	Unit
length	90	mm
width	50	mm
total height	35	mm
lid height	15	mm
wall thickness	3	mm
screw margin	0.1	mm
fit clearance	0.2	mm
cooling level	5
cooling zone(s)	cutouts on t...

📦 Model #2318

1 object(s)

- format STL

Tube adapter STL file ⌀ 158–118 mm (Length: 90 mm)

Inline fitting ⌀158 mm to ⌀118 mm in STL format. Final length of this connector is 90 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	158	mm
side A thickness	3	mm
side B length	30	mm
side B outer diameter	118	mm
side B thickness	3	mm
transition length	30	mm
axis offset	0	mm
ends fillet	no fillet

📦 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 #3158

2 object(s)

- format STL

Enclosure with screw-mounted lid STL 3D file: 130×130×140 mm (with ventilation on the lid)

Download this enclosure with lid in STL format. The dimensions are 130 mm long by 130 mm wide and 140 mm high. The lid only is 10 mm high. Side thickness is 4 mm. This enclosure features significant cooling area on the lid.

Parameter	Value	Unit
length	130	mm
width	130	mm
total height	140	mm
lid height	10	mm
wall thickness	4	mm
screw margin	0	mm
fit clearance	0.1	mm
cooling level	5
cooling zone(s)	cutouts on t...

📦 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 #4180

1 object(s)

- format STL

Tube adapter STL file ⌀ 15–12 mm (Length: 30 mm)

Inline tubing adapter ⌀15 mm to ⌀12 mm in STL format. Total length of this connector is 30 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a length of 10 mm, the smaller one of 15 mm. The ends are raw.

Parameter	Value	Unit
side A length	10	mm
side A outer diameter	15	mm
side A thickness	2	mm
side B length	15	mm
side B outer diameter	12	mm
side B thickness	2	mm
transition length	5	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #2106

1 object(s)

- format STL

O-ring STL 3D file ID 13 × CS 1 mm

STL model of rubber ring with ID 13 mm / thickness 1 mm. Final diameter resulting is therefore 15 mm.

Parameter	Value	Unit
inner diameter (ID)	13	mm
cross section (CS)	1	mm

📦 Model #2665

1 object(s)

- format STL

Tube adapter STL file ⌀ 83–63 mm (Length: 120 mm)

Tubing adapter ⌀83 mm to ⌀63 mm in STL 3D format. Length of this adapter is 120 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a sleeve length of 15 mm, the smaller one of 15 mm as well. The ends have no fillet.

Parameter	Value	Unit
side A length	15	mm
side A outer diameter	83	mm
side A thickness	3	mm
side B length	15	mm
side B outer diameter	63	mm
side B thickness	3	mm
transition length	90	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #4415

2 object(s)

- format STL

Round box with lid STL file ⌀ 115 mm - Height: 42 mm, Shell: 3 mm

Get this circular organizing box in 3D STL format. Its diameter is 115 mm and its total height is 42 mm. The wall width is 3 mm. A fillet located at the bottom of the box makes it easier to grab objects.

Parameter	Value	Unit
external diameter	115	mm
total height	42	mm
wall thickness	3	mm
fit clearance	0.2	mm
inner bottom fillet	1	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.