My favorite ashtray was in college, I found a small (less than 1 foot across) hubcap that worked perfectly in our dorm suite - with 8 smokers it filled fast.
I'll keep the ones I have, they're small, clear, flat ones, like Petri dishes, but with really thick glass, I bought a set of them years ago, half got used as ashtrays, and the rest I found were perfect for mixing varnishes and glazes for oil painting, and they're still used for that to this day - so I have more mixing dishes.
The only other one I have is a Waterford ashtray that was on my dad's desk, that's going on the shelf.
I'll keep the ones I have, they're small, clear, flat ones, like Petri dishes, but with really thick glass, I bought a set of them years ago, half got used as ashtrays, and the rest I found were perfect for mixing varnishes and glazes for oil painting, and they're still used for that to this day - so I have more mixing dishes.
The only other one I have is a Waterford ashtray that was on my dad's desk, that's going on the shelf.