Obviously you can make functional parts with a 3D-printer as well. 🙂
I reconstructed the Insulators for the headlamp-shell in Blender and printed one in PETG, as after almost 50 years the plastic crumbled and I needed replacements.
Worked well and looks good.
I noticed noises from the cylinder when engine was running. The cause was to much play between piston and cylinder. I bought a oversize piston (first oversize) and had the cylinder honed to fit the new piston & rings.