Is your STL ready to print: a checklist

What we check on upload

We accept STL and 3MF, up to 100 MB and three files per order. For each file we measure width, depth and height and check whether the mesh is closed: whether every edge sits on exactly two faces. If the piece does not fit the printer that goes with your material, or the mesh is open, you see that right away in the flow and the piece goes to a quote, so we can look at it by hand. Wall thicknesses and overhangs we do not measure automatically.

The list

Go through these nine points in your design program or slicer:

• Closed mesh: no holes, no open edges, no duplicate faces. Slicers sometimes fill holes themselves, but then they guess what you meant.
• Normals facing out: inside-out faces confuse a slicer. In most programs this is one button.
• One object, or deliberately several: a file with loose, floating bits prints as loose bits.
• Units and size: an STL has no unit. Check that 1 unit is 1 mm; a model of 25 units in inches is 635 mm.
• Wall thickness: for FDM at least 0.8 mm, preferably 1.2 mm; for resin at least 0.5 mm on load-bearing parts, thinner only for decoration.
• Details below the layer height: a line 0.1 mm high disappears on FDM at 0.16 mm layers and stays on resin at 0.05 mm.
• Overhangs: parts that stick out beyond roughly 45 degrees need support and keep a mark there. Rotate the model if you can.
• A flat bottom, or a deliberate orientation: a sphere on one point does not adhere; a face of a few millimetres does.
• Build volume: FDM up to 250 × 250 × 250 mm, resin up to 127 × 80 × 160 mm. Larger can be done in parts, with a joint you design yourself.

What goes wrong in practice

Three mistakes are common: a model in inches or centimetres, which therefore arrives 25.4 or 10 times too large or too small; a mesh that looks closed in the design program but has open edges on export, usually at a boolean; and walls that look fine on screen but are like paper after printing. All three you can see beforehand in your slicer.

What you do not have to do

Supply supports, hollow the model, or set the layer height in the file. We do that per printer and per material. A 3MF with colours per part is welcome too, but we print one colour per print; more colours means separate parts that click together.

Frequently asked questions

Can I supply an OBJ or STEP?

No, only STL and 3MF. Most design programs export both without loss.

Do you repair an open mesh?

We see on upload that it is open and then look at it by hand through the quote route. Small holes can often be repaired; a model made of loose shells cannot.

May I have a file from the internet printed?

Only if the licence allows having it printed (with an NC licence that is not certain: ask the maker) and it is not a protected character. You confirm that on upload.