waterpoof printer?

A laser printer perhaps?, printing on white acetate (white transparency film) this combination would be completely water proof and last for a long time.

A cheap consumer colour laser though may be a challenge.

actually I remember going to Best Buy in Los Angeles, and they had a demo of a print sample in a water bottle and the lady would shake the bottle really hard to show how the ink is really good. I think it was either Epson or Canon and you have to get their special paper thats resistant to water or something like that. Its possible just fergot >< what model i saw.

Good luck share your results if you find anything on it.

Thermal printer maybe? I know they are the only ones that print on DVDs that are truly waterproof.

What are you asking for - waterproof or paint proof?
If your paints have an oil or solvent base, thats a different requirement.

Thermal transfer printing (transfer ribbon)
Solid ink (Xerox 'wax crayon' printing)
Dye Sublimation printing
Some inkjet printing if using waterfast ink formulations

Each have their own plusses and minuses. The solid ink printing is waterproof and can print on various media, like tyvek and canvas. But it is not heat proof at all. Inkjet printing is highly dependent on the media. Dye Sublimation can only use specialized media.

My Epson is supposed to be waterproof, I haven't put prints into water or anything, but I've gotten some documents wet, and they didn't smear or anything.