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

Round box with lid STL 3D file ⌀ 80 mm - Height: 50 mm, Shell: 3 mm

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

Shelf bracket 110×110 mm STL file, thickness 8 mm, hole diameter 6 mm

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

Round-to-Rectangular Tube Adapter STL file ⌀80 mm to 80×80 mm, thickness 3 mm

Small parts organizer with 1 drawer 80×80×80 mm STL file, thickness: 3 mm

Tube adapter STL file ⌀ 100–51 mm (Length: 160 mm)

Round air vent STL 3D file ∅ 70 mm, slat angle: 45° with central reinforcement

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

U-shaped handle STL 3D file 50×140×14 mm (Center-to-center 126 mm) 📦 #988

1 object(s) - format STL

View of object #0

Latest user-generated 3D models

Rectangular-base box with lid STL 3D file – 85×65×47 mm, wall thickness 3 mm 📦 #9507

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 #1162

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 250–200 mm (Length: 140 mm)

Tube fitting ⌀250 mm to ⌀200 mm in STL 3D format. Total length of this sleeve is 140 mm. The thickness of the tubes is identical: 5 mm. The larger-diameter tube has a length of 60 mm, the smaller one of 50 mm. The ends have a fillet on the outside to facilitate the connection of the two tubes.

Parameter	Value	Unit
side A length	60	mm
side A outer diameter	250	mm
side A thickness	5	mm
side B length	50	mm
side B outer diameter	200	mm
side B thickness	5	mm
transition length	30	mm
axis offset	0	mm
ends fillet	fillet on th...

📦 Model #3096

1 object(s)

- format STL

Honeycomb grille STL 3D file, 210x148mm, mesh: 10mm

Download this rectangular protective grid file in STL format. The overall size is 210x148 mm, with very large 10 mm cell size for maximum airflow. This grid provides both mechanical protection and airflow.

Parameter	Value	Unit
length or center-to-center	210	mm
width or center-to-center	148	mm
mesh size	10	mm
dual color	no
holes	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 #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 #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 #3420

1 object(s)

- format STL

Protective grid STL 3D file, center-to-center: 38x38mm, mesh: 5mm - Ø3mm

3D fan guard file in STL format. Mounting holes are placed at the four corners (center-to-center 38x38 mm), each with a diameter of Ø3 mm. The overall dimensions reach 44x44 mm, with regular 5 mm cell size for balanced airflow and protection. This grid functions as both a mechanical guard and a ventilation panel.

Parameter	Value	Unit
length or center-to-center	38	mm
width or center-to-center	38	mm
mesh size	5	mm
dual color	no
holes	yes
hole diameter	3	mm

📦 Model #1344

2 object(s)

- format STL

Round box with lid STL file ⌀ 110 mm - Height: 25 mm, Shell: 3 mm

Get this cylindrical box in STL format. Its diameter is 110 mm and its total height is 25 mm. The wall width is 3 mm. A fillet located at the bottom of the box makes it easier to grip objects.

Parameter	Value	Unit
external diameter	110	mm
total height	25	mm
wall thickness	3	mm
fit clearance	0.1	mm
inner bottom fillet	1	mm

📦 Model #4417

2 object(s)

- format STL

Enclosure with screw-mounted lid STL 3D file: 120×100×35 mm (with ventilation on the lid and under the enclosure)

Download this enclosure with lid in 3D STL format. The dimensions are 120 mm long by 100 mm wide and 35 mm high. The lid is 10 mm high. Wall thickness is 2 mm. This enclosure has significant cooling area on the lid and under the base.

Parameter	Value	Unit
length	120	mm
width	100	mm
total height	35	mm
lid height	10	mm
wall thickness	2	mm
screw margin	0	mm
fit clearance	0.1	mm
cooling level	8
cooling zone(s)	cutouts on b...

📦 Model #2013

3 object(s)

- format STL

Small parts organizer with 3 drawers 90×65×150 mm STL file, thickness: 3 mm

File of a storage organizer in 3D STL format. This model contains 3 boxes, arranged in 3 rows and 1 columns. Practically speaking, this means 3 rows of 1 boxes. Each box measures 90 mm wide, 65 mm high, and 150 mm deep. The wall thickness is 3 mm, which makes the structure sturdy. The boxes come with 2 dividers each, which allows up to 3 compartments per box and up to 9 compartments in total. The total size of the structure measure 102.5 x 217.5 x 159 mm. All the objects in this model were designed to be printable without support.

Parameter	Value	Unit
number of rows	3
number of columns	1
inner drawer depth	150	mm
inner drawer width	90	mm
inner drawer height	65	mm
wall thickness	3	mm
removable divider	two divider ...

📦 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 #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 #3106

2 object(s)

- format STL

Enclosure with screw-mounted lid STL 3D file: 52×40×20 mm

Enclosure model with lid in 3D STL format. The dimensions are 52 mm long by 40 mm wide and 20 mm high. The cover is 15 mm high. Wall thickness is 2 mm. The enclosure does not feature cooling.

Parameter	Value	Unit
length	52	mm
width	40	mm
total height	20	mm
lid height	15	mm
wall thickness	2	mm
screw margin	0	mm
fit clearance	0.1	mm
cooling zone(s)	no cutouts

📦 Model #2553

1 object(s)

- format STL

Tube adapter STL file ⌀ 39–31 mm (Length: 80 mm)

Tube connector ⌀39 mm to ⌀31 mm in STL format. Length of this adapter 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 40 mm. The ends feature an external fillet.

Parameter	Value	Unit
side A length	20	mm
side A outer diameter	39	mm
side A thickness	2	mm
side B length	40	mm
side B outer diameter	31	mm
side B thickness	2	mm
transition length	20	mm
axis offset	0	mm
ends fillet	fillet on th...

📦 Model #820

1 object(s)

- format STL

U-shaped handle STL 3D file 35×100×14 mm (Center-to-center 86 mm)

Download this model of a basic U-shaped handle. The external dimensions are 35×100×14 mm. The handle features a square cross-section and a softened transition. The bores are 4 mm diameter with a center-to-center distance of 86 mm.

Parameter	Value	Unit
width	35	mm
length	100	mm
thickness	14	mm
shape (0:square,1:circle)	0
transition (0:right,1:rounded)	1
fillet radius	0	mm
hole diameter	4	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 #4398

1 object(s)

- format STL

Honeycomb grille STL file, 180x165mm, mesh: 3mm

Download this rectangular honeycomb grid model in STL format. The overall size is 180x165 mm, with extra fine 3 mm cell size for maximum protection. This grid serves as both a protective guard and a ventilation panel.

Parameter	Value	Unit
length or center-to-center	180	mm
width or center-to-center	165	mm
mesh size	3	mm
dual color	no
holes	no

📦 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 #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 #1934

1 object(s)

- format STL

Washer / Flat Gasket STL 3D file ⌀ID: 10 mm ⌀OD: 20 mm thickness: 10 mm + chamfer

3D file of washer / gasket in STL format. This model features an inner diameter of ⌀10 mm and an outer diameter of ⌀20 mm. The total thickness is 10 mm. A chamfer is applied on the inner diameter with a value of 1 mm.

Parameter	Value	Unit
inner diameter	10	mm
outer diameter	20	mm
thickness	10	mm
finish	chamfer
finish position	inner
sides	one side
finish value	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 #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 #1918

1 object(s)

- format STL

Tube adapter STL file ⌀ 50–45 mm (Length: 90 mm)

Straight tube coupler ⌀50 mm to ⌀45 mm in STL 3D format. Length of this adapter is 90 mm. The thickness of the tubes is identical: 5 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	50	mm
side A thickness	5	mm
side B length	30	mm
side B outer diameter	45	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 #4371

1 object(s)

- format STL

Support bracket 250×250 mm STL 3D file, thickness 6 mm, hole diameter 6 mm

Model of a support bracket with a central reinforcement in STL 3D format. The dimensions are 250 mm in length, 250 mm in height, 20 mm in width, and 6 mm in thickness. The screw holes have a diameter of 6 mm. Chamfers are applied to the holes to seat the screw heads. The reinforcing bar enhances mechanical strength and includes two clearances for screwdriver access. Support generation is not required for printing this bracket, printed flat on the print bed.

Parameter	Value	Unit
length	250	mm
height	250	mm
width	20	mm
thickness	6	mm
hole diameter	6	mm
chamfer on the holes	yes

📦 Model #4502

1 object(s)

- format STL

Pipe elbow STL 3D file 45° ⌀OD: 72 mm ⌀ID: 64 mm thickness: 4 mm

Model of an elbow with a 45° angle in STL format. This pipe elbow has an external diameter of 72 mm and an internal diameter of 64 mm. The tube thickness is therefore 4 mm. End fillets make it easier to insert.

Parameter	Value	Unit
outer diameter	72	mm
inner diameter	64	mm
angle	45	°
end fillets	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 #2245

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀50 mm to 35×25 mm, thickness 3 mm

Download this 3D file in STL format of a round-to-rectangular adapter with an outer diameter of ⌀50 mm and a rectangular section with inner dimensions 35×25 mm. The wall thickness is 3 mm and the total length is 100 mm.

Parameter	Value	Unit
cylinder outer diameter	50	mm
cylinder inlet length	25	mm
rectangle internal length	35	mm
rectangle internal height	25	mm
rectangle inlet length	25	mm
offset Z	0	mm
offset Y	0	mm
total length	100	mm
thickness	3	mm
chamfer	no chamfer

📦 Model #4540

1 object(s)

- format STL

Tubing adapter STL 3D file ⌀ 95–80 mm (Length: 255 mm)

Straight tube coupler ⌀95 mm to ⌀80 mm in STL format. Final length of this reducer is 255 mm. The thickness of the tubes is identical: 10 mm. The larger-diameter tube has a sleeve length of 150 mm, the smaller one of 100 mm. The ends feature an external fillet to facilitate the connection of the two tubes.

Parameter	Value	Unit
side A length	150	mm
side A outer diameter	95	mm
side A thickness	10	mm
side B length	100	mm
side B outer diameter	80	mm
side B thickness	10	mm
transition length	5	mm
axis offset	0	mm
ends fillet	fillet on th...

📦 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

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.