We have used our laser to do two color paint jobs before. There are several methods including pre-painting and etching into the bottom color or simply making a mask using the included paper scratch guard on the material. However, Three colors is a bit tricky. So we try to tackle this with the power of LASERS and some transfer tape as a mask.
We did find that after we finished the paint job something went... horribly wrong. Still not sure what happened but clear coat we used cracked but only on the acrylic and in specific areas. We ended up using an airbrush acrylic gloss coat to protect it after fixing the issues several times. We have yet to have the same issue again. Could have been some oil or dirt transferred to the prop before it was finished but we fixed it and sent it out to its forever home.
Materials used in this video:
We also used a trick to add the a pvc to a 3d printed part that was undersized. It was easier then reprinting and sanding again! We used Gorilla Glue to fill in the spaces of the exposed infill and hold the piece. We even made a tutorial for it!