I tried making an ashtray just from stuff I'd find near my place last summer.
First two attempts broke during firing. The third survived but the pieces came apart in my hands at one point and the bottom fell to the floor and broke too.
I've been firing these in a primitive oven made of stone bricks, they also mostly shattered from the heat and by the end I didn't have enough to make a new oven.
I have stopped smoking since then, so I don't need an ashtray anymore anyway...
Gonna try again this summer.
Do you guys do any pottery