I'm making a wearable mask that will have fabric around it and foam in the inside, meaning it will have to be washed if worn for a long time. There wouldn't really be a way to avoid getting the plastic part wet. I've already printed the plastic part with PLA. I want to get a really smooth finish and I've heard that Bondo glazing and spot putty is great for filling pin holes and very tiny ridges. I absent mindly bought it after seeing "waterproof" in an article it was featured in. I can't actually find "waterproof" in any of its product descriptions, though.

I know that the putty absorbs water, so I'm afraid it might expand and crack after I've primed and painted it. I've also seen that some wood filler is waterproof and usable on PLA, so I'm thinking that might be a better option. Any thoughts on what I should use, or if the bondo is ok?

Thanks in advance