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Round air vent STL 3D file ∅ 152 mm, slat angle: 45° with central reinforcement

Tube support clip Ø200 mm STL file · Round head screw Ø8 mm

Rectangular-base box with lid STL 3D file – 120×80×50 mm, wall thickness 3 mm

Distribution manifold 3 ways STL file – Outer diameter 50 mm, wall thickness 10 mm

Oval duct transition adapter STL file 80.1x80 mm to 80x40 mm – transition: 20 mm

Tube adapter STL file ⌀ 50–40 mm (Length: 45 mm)

Pipe elbow STL 3D file 180° ⌀OD: 20 mm ⌀ID: 16 mm thickness: 2 mm

Round-to-Rectangular Tube Adapter STL 3D file ⌀20 mm to 20×20 mm, thickness 2 mm + offset

Protective grid STL 3D file, center-to-center: 70x70mm, mesh: 10mm - Ø4mm

L-bracket 200×200 mm STL file, thickness 5 mm, hole diameter 6 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-base box with lid STL 3D model – 170×95×110 mm, wall thickness 3 mm 📦 #6422

2 object(s) - format STL

Latest user-generated 3D models

Honeycomb grille STL 3D file, center-to-center: 110x110mm, mesh: 3mm - Ø3mm 📦 #12037

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 #2844

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 12–6 mm (Length: 65 mm)

Straight tube reducer ⌀12 mm to ⌀6 mm in STL format. Total length of this connector is 65 mm. The thickness of the tubes is identical: 2 mm. The larger-diameter tube has a sleeve length of 20 mm, the smaller one of 20 mm as well. The ends have no fillet.

Parameter	Value	Unit
side A length	20	mm
side A outer diameter	12	mm
side A thickness	2	mm
side B length	20	mm
side B outer diameter	6	mm
side B thickness	2	mm
transition length	25	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 #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 #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 #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 #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 #2111

1 object(s)

- format STL

Multi-compartment box STL file: 18 compartments of 100×100×50 mm

This STL 3D model features 18 storage spaces measuring 100×100×50mm each. The total dimensions of the box are 614×308×52mm. Fillets of 2mm applied to all compartments make it easier to grasp items stored in the box.

Parameter	Value	Unit
number of rows	3
number of columns	6
compartment length	100	mm
compartment width	100	mm
compartment height	50	mm
wall thickness	2	mm
compartment fillet (radius)	2	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 #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 #4240

2 object(s)

- format STL

Small parts organizer with 32 drawers 20×20×20 mm STL file, thickness: 2 mm

3D model of a storage box with drawers in 3D STL format. This model features 32 boxes, arranged in 4 rows and 8 columns. In detail, this means 4 rows of 8 boxes. Each box measures 20 mm wide, 20 mm high, and 20 mm deep. The wall thickness is 2 mm. The total size of the structure are 214 x 100 x 26 mm. All the objects in this model were designed to be printed without support generation.

Parameter	Value	Unit
number of rows	4
number of columns	8
inner drawer depth	20	mm
inner drawer width	20	mm
inner drawer height	20	mm
wall thickness	2	mm
removable divider	none

📦 Model #1581

1 object(s)

- format STL

O-ring STL file ID 28.5 × CS 3.5 mm

STL file of rubber ring with dimensions ID (inner diameter) 28.5 mm by CS (cross section) 3.5 mm. Outer diameter (OD) resulting is 35.5 mm.

Parameter	Value	Unit
inner diameter (ID)	28.5	mm
cross section (CS)	3.5	mm

📦 Model #912

1 object(s)

- format STL

U-shaped handle STL file 50×100×10 mm (Center-to-center 90 mm)

Download this STL model of a simple U-shaped handle. The external dimensions are 50×100×10 mm. The handle features a square section combined with a rounded transition. The bores are 6 mm diameter and have a 90 mm center-to-center distance.

Parameter	Value	Unit
width	50	mm
length	100	mm
thickness	10	mm
shape (0:square,1:circle)	0
transition (0:right,1:rounded)	1
fillet radius	0	mm
hole diameter	6	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 #1381

1 object(s)

- format STL

Pipe elbow STL file 60° ⌀OD: 32 mm ⌀ID: 28 mm thickness: 2 mm

Model of a pipe elbow with a 60° angle in STL format. This pipe elbow has an outer diameter of 32 mm and an inner diameter of 28 mm. The tube thickness is therefore 2 mm. The ends feature fillets to make it easier to assemble.

Parameter	Value	Unit
outer diameter	32	mm
inner diameter	28	mm
angle	60	°
end fillets	yes

📦 Model #1410

1 object(s)

- format STL

Pipe elbow STL 3D file 90° ⌀OD: 17.5 mm ⌀ID: 15.5 mm thickness: 1 mm

3D model of a pipe elbow with a 90° angle in STL format. This elbow features an external diameter of 17.5 mm and an internal diameter of 15.5 mm. The tube thickness is therefore 1 mm.

Parameter	Value	Unit
outer diameter	17.5	mm
inner diameter	15.5	mm
angle	90	°
end fillets	no

📦 Model #5925

2 object(s)

- format STL

Rectangular-base box with lid STL 3D file – 100×50×50 mm, wall thickness 3 mm

Rectangular-base box with a lid available as a STL 3D file. Box size: 100 mm × 50 mm × 50 mm (L × W × H). Wall thickness is 3 mm. Interior and exterior edges are rounded. A small clearance is included to ensure a precise fit between the box and the lid. The inner dimensions excluding rounding are 94 mm × 44 mm × 44 mm.

Parameter	Value	Unit
length	100	mm
width	50	mm
height	50	mm
wall thikness	3	mm

📦 Model #4452

1 object(s)

- format STL

Oval duct transition adapter STL file 100x70 mm to 80x40 mm – transition: 20 mm

Oval pipe adapter provided as a STL 3D file. The internal cross-section on side A is 100x70 mm, while on side B it is 80x40 mm. You get a sleeve of 5 mm on side A and 10 mm on side B. The transition section is 20 mm long, for a final overall length of 35 mm. The shell is relatively thick, with a wall thickness of 4 mm. External chamfers are added at the ends to make it easier to insert the adapter into ducts or hoses.

Parameter	Value	Unit
side A internal width	100	mm
side A internal height	70	mm
sleeve length on side A	5	mm
side B internal width	80	mm
side B internal height	40	mm
sleeve length on side B	10	mm
thickness	4	mm
transition length	20	mm
Y offset	0	mm
Z offset	0	mm
end chamfers	outside

📦 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 #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 #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 #2247

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL file ⌀119 mm to 114×79 mm, thickness 3 mm + offset

Download this model in STL format of a round-to-rectangular adapter with an external diameter of ⌀119 mm and a rectangular section with inner dimensions 114×79 mm. The shell thickness is 3 mm and the overall length is 100 mm. The adapter has an offset of 2 mm along the Y axis and 17.5 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	119	mm
cylinder inlet length	30	mm
rectangle internal length	114	mm
rectangle internal height	79	mm
rectangle inlet length	30	mm
offset Z	17.5	mm
offset Y	2	mm
total length	100	mm
thickness	3	mm
chamfer	no chamfer

📦 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 #2341

1 object(s)

- format STL

Washer / Flat Gasket STL 3D file ⌀ID: 16.5 mm ⌀OD: 25.0 mm thickness: 3.5 mm

File of washer / gasket in STL format. This part has an inner diameter of ⌀16.5 mm and an outer diameter of ⌀25.0 mm. The total thickness is 3.5 mm. This part has no finish present.

Parameter	Value	Unit
inner diameter	16.5	mm
outer diameter	25.0	mm
thickness	3.5	mm
finish	none

📦 Model #1862

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀60 mm to 100×48 mm, thickness 2 mm + offset

Download this 3D model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀60 mm and a rectangular section with internal dimensions 100×48 mm. The shell thickness is 2 mm and the overall length is 100 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.

Parameter	Value	Unit
cylinder outer diameter	60	mm
cylinder inlet length	30	mm
rectangle internal length	100	mm
rectangle internal height	48	mm
rectangle inlet length	30	mm
offset Z	15	mm
offset Y	0	mm
total length	100	mm
thickness	2	mm
chamfer	chamfers on ...

📦 Model #2289

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 158–118 mm (Length: 65 mm)

Tube adapter ⌀158 mm to ⌀118 mm in STL format. Final length of this fitting is 65 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 are raw.

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	5	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #1225

1 object(s)

- format STL

Multi-compartment box STL file: 4 compartments of 100×50×100 mm

This parametric storage box features 4 storage spaces measuring 100×50×100mm each. The total dimensions are 215×115×105mm. A 4mm fillet applied to all compartments help with item retrieval stored in the compartments. The dividers are particularly thick.

Parameter	Value	Unit
number of rows	2
number of columns	2
compartment length	100	mm
compartment width	50	mm
compartment height	100	mm
wall thickness	5	mm
compartment fillet (radius)	4	mm

📦 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 #2797

1 object(s)

- format STL

Tubing adapter STL file ⌀ 97–70 mm (Length: 90 mm)

Tubing adapter ⌀97 mm to ⌀70 mm in STL 3D format. Total length of this coupler 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 are not rounded.

Parameter	Value	Unit
side A length	30	mm
side A outer diameter	97	mm
side A thickness	3	mm
side B length	30	mm
side B outer diameter	70	mm
side B thickness	3	mm
transition length	30	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #2653

3 object(s)

- format STL

Small parts organizer with 20 drawers 30×12×60 mm STL 3D file, thickness: 2 mm

Model of storage drawers in 3D STL format. This model contains 20 drawers, arranged in 4 rows and 5 columns. In detail, this means 4 rows of 5 drawers. Each drawer comes with an inner space of 30 mm wide, 12 mm high, and 60 mm deep. The wall thickness is 2 mm. The drawers come with 2 dividers each, which allows up to 3 sections per drawer and up to 60 compartments in total. The external dimensions of the structure measure 184.5 x 68 x 66 mm. All the objects in this model were designed to be printable without support generation.

Parameter	Value	Unit
number of rows	4
number of columns	5
inner drawer depth	60	mm
inner drawer width	30	mm
inner drawer height	12	mm
wall thickness	2	mm
removable divider	two divider ...

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.