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Hollow tube STL 3D file OD 100 mm, ID 92 mm, length 50 mm

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

Round box with lid STL file ⌀ 45 mm - Height: 40 mm, Shell: 2 mm

Small parts organizer with 4 drawers 100×10×50 mm STL 3D file, thickness: 2 mm

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

Tube adapter STL file ⌀ 100–60 mm (Length: 70 mm)

Enclosure with screw-mounted lid STL file: 90×50×40 mm (with ventilation on the lid)

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

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

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

Plate STL file 100×12×87 mm 📦 #782

1 object(s) - format STL

Latest user-generated 3D models

Tubing adapter STL file ⌀ 162–132 mm (Length: 110 mm) 📦 #11746

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 #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 #1656

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀85 mm to 105×50 mm, thickness 2 mm + offset

Download this model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀85 mm and a rectangular section with internal dimensions 105×50 mm. The shell thickness is 2 mm and the overall length is 150 mm. The adapter has an offset of 15 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	85	mm
cylinder inlet length	50	mm
rectangle internal length	105	mm
rectangle internal height	50	mm
rectangle inlet length	46	mm
offset Z	15	mm
offset Y	0	mm
total length	150	mm
thickness	2	mm
chamfer	no chamfer

📦 Model #4429

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀103 mm to 290×28 mm, thickness 3 mm

Download this model in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀103 mm and a rectangular section with internal dimensions 290×28 mm. The wall thickness is 3 mm and the total length is 148 mm.

Parameter	Value	Unit
cylinder outer diameter	103	mm
cylinder inlet length	50	mm
rectangle internal length	290	mm
rectangle internal height	28	mm
rectangle inlet length	50	mm
offset Z	0	mm
offset Y	0	mm
total length	148	mm
thickness	3	mm
chamfer	no chamfer

📦 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 #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 #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 #2996

1 object(s)

- format STL

Tube adapter STL file ⌀ 60–35 mm (Length: 240 mm)

Straight tube fitting ⌀60 mm to ⌀35 mm in STL 3D format. Length of this adapter is 240 mm. The thickness of the tubes is identical: 3 mm. The larger-diameter tube has a sleeve length of 80 mm, the smaller one of 80 mm as well. The ends are raw.

Parameter	Value	Unit
side A length	80	mm
side A outer diameter	60	mm
side A thickness	3	mm
side B length	80	mm
side B outer diameter	35	mm
side B thickness	3	mm
transition length	80	mm
axis offset	0	mm
ends fillet	no fillet

📦 Model #4515

1 object(s)

- format STL

Tubing adapter STL file ⌀ 60–58 mm (Length: 45 mm)

Straight tube fitting ⌀60 mm to ⌀58 mm in STL 3D format. Total length of this adapter is 45 mm. The thickness of the tubes is identical: 4 mm. The larger-diameter tube has a 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	60	mm
side A thickness	4	mm
side B length	20	mm
side B outer diameter	58	mm
side B thickness	4	mm
transition length	5	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 #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 #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 #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 #2269

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 124–103 mm (Length: 120 mm)

Straight sleeve ⌀124 mm to ⌀103 mm in STL format. Total length of this coupler is 120 mm. The thickness of the tubes is identical: 6 mm. The larger-diameter tube has a length of 40 mm, the smaller one of 40 mm as well. The ends are rounded to make tube connection easier.

Parameter	Value	Unit
side A length	40	mm
side A outer diameter	124	mm
side A thickness	6	mm
side B length	40	mm
side B outer diameter	103	mm
side B thickness	6	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 #3253

1 object(s)

- format STL

O-ring STL 3D file ID 49 × CS 3.6 mm

STL model of circular seal with Internal diameter 49 mm / section thickness 3.6 mm. Outer diameter (OD) is therefore 56.2 mm.

Parameter	Value	Unit
inner diameter (ID)	49	mm
cross section (CS)	3.6	mm

📦 Model #1919

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL 3D file ⌀80 mm to 60×60 mm, thickness 2 mm

Download this 3D model in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀80 mm and a rectangular section with inner dimensions 60×60 mm. The shell thickness is 2 mm and the overall length is 100 mm. Chamfers are present on the outside of the cylindrical end and on the inside of the rectangular end.

Parameter	Value	Unit
cylinder outer diameter	80	mm
cylinder inlet length	30	mm
rectangle internal length	60	mm
rectangle internal height	60	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	100	mm
thickness	2	mm
chamfer	chamfers on ...

📦 Model #2630

1 object(s)

- format STL

Right-angle bracket 150×150 mm STL 3D file, thickness 12 mm, hole diameter 8 mm

Download this model of an angle bracket with a central reinforcing bar in STL 3D format. The dimensions are 150 mm in length, 150 mm in height, 30 mm in width, and 12 mm in thickness. The drill holes have a diameter of 8 mm. Chamfers are done to the holes to seat the screw heads. The reinforcing bar reduces bending and provides two clearances for screwdriver access. Support generation is not required for printing this bracket, printed flat on the build plate.

Parameter	Value	Unit
length	150	mm
height	150	mm
width	30	mm
thickness	12	mm
hole diameter	8	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 #1981

1 object(s)

- format STL

Round-to-Rectangular Tube Adapter STL file ⌀35 mm to 10×5 mm, thickness 3 mm

File in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀35 mm and a rectangular section with inner dimensions 10×5 mm. The wall thickness is 3 mm and the total length is 50 mm. A chamfer is present on the outside of the cylindrical end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	35	mm
cylinder inlet length	5	mm
rectangle internal length	10	mm
rectangle internal height	5	mm
rectangle inlet length	5	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	3	mm
chamfer	chamfer on t...

📦 Model #3263

1 object(s)

- format STL

Washer / Flat Gasket STL file ⌀ID: 42 mm ⌀OD: 46 mm thickness: 20 mm + fillet

Download this 3D file of gasket / washer in STL format. This model features an inner diameter of ⌀42 mm and an outer diameter of ⌀46 mm. The thickness is 20 mm. A fillet is applied on the inner diameter with a value of 1 mm.

Parameter	Value	Unit
inner diameter	42	mm
outer diameter	46	mm
thickness	20	mm
finish	fillet
finish position	inner
sides	one side
finish value	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 #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 #1997

1 object(s)

- format STL

Tube adapter STL 3D file ⌀ 80–66 mm (Length: 120 mm)

Straight tube reducer ⌀80 mm to ⌀66 mm in STL format. Total length of this fitting is 120 mm. The larger-diameter tube has a thickness of 3 mm and a sleeve length of 40 mm. The smaller-diameter tube has a thickness of 20 mm and a length of 30 mm. The ends are raw.

Parameter	Value	Unit
side A length	40	mm
side A outer diameter	80	mm
side A thickness	3	mm
side B length	30	mm
side B outer diameter	66	mm
side B thickness	20	mm
transition length	50	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 #1605

1 object(s)

- format STL

Pipe elbow STL file 90° ⌀OD: 20 mm ⌀ID: 16 mm thickness: 2 mm

File of an elbow with a 90° angle in STL format. This pipe elbow has an external diameter of 20 mm and an internal diameter of 16 mm. The tube thickness is therefore 2 mm. The ends feature fillets to make it easier to assemble.

Parameter	Value	Unit
outer diameter	20	mm
inner diameter	16	mm
angle	90	°
end fillets	yes

📦 Model #1237

1 object(s)

- format STL

Tube adapter STL file ⌀ 147–75 mm (Length: 180 mm)

Tube junction ⌀147 mm to ⌀75 mm in STL format. Final length of this junction is 180 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 40 mm. The axes of the tubes are offset by 35.9 mm. The ends have no fillet.

Parameter	Value	Unit
side A length	20	mm
side A outer diameter	147	mm
side A thickness	2	mm
side B length	40	mm
side B outer diameter	75	mm
side B thickness	2	mm
transition length	120	mm
axis offset	35.9	mm
ends fillet	no fillet

📦 Model #2807

2 object(s)

- format STL

Small parts organizer with 6 drawers 70×70×90 mm STL file, thickness: 2 mm

Model of a storage box with drawers in 3D STL format. This model features 6 boxes, arranged in 2 rows and 3 columns. Practically speaking, this means 2 rows of 3 boxes. Each box provides an inside space of 70 mm wide, 70 mm high, and 90 mm deep. The wall thickness is 2 mm. The external dimensions of the structure are 231.5 x 151 x 96 mm. All the objects in this model were designed to be printable without support.

Parameter	Value	Unit
number of rows	2
number of columns	3
inner drawer depth	90	mm
inner drawer width	70	mm
inner drawer height	70	mm
wall thickness	2	mm
removable divider	none

📦 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 #1142

2 object(s)

- format STL

Enclosure with screw-mounted lid STL 3D file: 200×120×45 mm (with ventilation on the lid and under the enclosure)

Download this enclosure with lid in 3D STL format. The dimensions are 200 mm long by 120 mm wide and 45 mm high. The cover is 15 mm high. Side thickness is 4 mm. This enclosure has significant cooling area on the lid and under the base.

Parameter	Value	Unit
length	200	mm
width	120	mm
total height	45	mm
lid height	15	mm
wall thickness	4	mm
screw margin	0	mm
fit clearance	0.1	mm
cooling level	8
cooling zone(s)	cutouts on b...

📦 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.