Question 1

Are 3D printed extrusion connectors strong enough?

Accepted Answer

For light and non-structural jobs, absolutely. For load-bearing frames use metal brackets and metal T-nuts. Printed parts shine when you need a non-standard angle, a size nobody sells, a quick fix, or a bracket that also holds a sensor or cable clip. Use PETG or PLA+ with at least 60% infill and 3-4 perimeters.

Question 2

What is the difference between 2020, 3030 and 4040?

Accepted Answer

The number is the cross-section size in millimetres: 2020 is 20x20 mm with a 6 mm slot opening; 3030 and 4040 have an 8 mm slot; 4545 has a 10 mm slot. Use 2020 for small mechanisms and 3D printer frames, 3030 for medium structures, and 4040 or larger for heavy loads or long spans.

Question 3

Can a printed profile be used as a structural part?

Accepted Answer

It is fine for light loads and for checking fit and appearance, but it should not replace real aluminum extrusion in a load-bearing frame. Typical uses are assembly mock-ups, scale models, display samples and teaching.

Question 4

How much tolerance should I leave on holes and slots?

Accepted Answer

Printed parts shrink or swell, so leave 0.1-0.2 mm for a tight fit and 0.3-0.5 mm for a loose fit. That is exactly what the fit clearance parameter does. Always measure your real profile with calipers first.

Question 5

How do I get threads in a printed T-nut?

Accepted Answer

Use a heat-set brass insert (M3/M4/M5) and melt it in with a soldering iron - never print the thread itself. The default centre hole in the T-nut generator is sized to a typical insert outer diameter; adjust it to match the inserts you bought.

Question 6

How do the 45° mitre cuts work?

Accepted Answer

For rectangular frames, picture frames and light boxes, mitre both ends at 45° so the two pieces meet at a clean right angle. Pick the mitre direction to match how the frame sits: Height for an upright frame, Width for a flat one.

Question 7

Can I import the STL into CAD software?

Accepted Answer

STL is a mesh format and imports into most CAD and slicer software. If you need parametric editing, use this tool to settle the dimensions and then rebuild the solid in CAD.

Question 8

Do I need to install anything or be online?

Accepted Answer

Nothing to install - just open the page. The first load fetches the 3D engine from a CDN, after that all model generation and STL export happen locally in your browser. Your model data never leaves your machine.

Series	Common models	Cross-section (mm)	Slot opening	Inner channel	Slot depth	Centre bore	Common bolts
20 series	2020 / 2040 / 2060	20×20 · 20×40 · 20×60	6 mm	8 mm	4.6 mm	φ4.2	M4 / M5
30 series	3030 / 3060	30×30 · 30×60	8 mm	11 mm	6.2 mm	φ6.8	M6 / M8
40 series	4040 / 4080	40×40 · 40×80	8 mm	11 mm	6.2 mm	φ6.8	M6 / M8
45 series	4545 / 4590	45×45 · 45×90	10 mm	14 mm	7.8 mm	φ8.5	M8 / M10

Connector	Best for	Notes
Corner bracket (L)	90° joints	Flat against the profile, needs T-nuts — the most versatile option
Outside corner (3D)	Wrapping an outside corner	Two load-bearing faces plus a triangular gusset for stiffness
T-nut / spring nut	Every bolted joint	Slides into the slot and locks any connector in place
Hidden joiner	End-to-end or concealed joints	Fits the centre bore, keeps the frame looking clean
Splice plate	Extending or joining profiles	Bridges two profiles and spreads the load

What this tool does

Aluminum extrusion size chart

Which connector should I use?

3D printing tips for extrusion parts

Typical use cases

Frequently asked questions