Fonts are baked into the server image. Check what's actually installed with docker compose exec app fc-list — a font here only works if its download succeeded during build.
Outline
Colored layer traced around the letters
custom colour
custom colour
3MF keeps the colours as separate parts. STL is one plain mesh. OBJ is for
Blender and the like, not for printing.
A recipe of everything on this page, so you can come back to it later.