We use to do this 20+ years ago if you needed a specific colour or needed a crazy design. Back then we used solvent based screen printing inks. Light coats helped for the vinyl not to melt. Enter acrylic paints. I finally decided to try and see if Schmincke's Aero Lak will help seal acrylic paints. I tried it with Illustration Colours and Schmincke Aero Colour. I just wiped the vinyl with some alcohol and sprayed some rainbows. Then cleared it with the Aero Lak and pushed it through my Cameo to cut some letter. "Raindbow" is the Illustration colours and "Schmincke" is, well, the Aero Colour. The toughness is not affected by which paints you use, it is the same on both brands. Here I just used my fingernail to try and scratch it of. Please not that it is still water soluble so with some rubbing with a wet rag I could remove it all.