Wood turned ashtrays lend themselves to all sorts of odd designs, for a formal occasion the plain dark wood looks good, but for a ‘born again hippy’ how about a bit of colour, the biggest concern I would stress when making ashtrays is make the base heavy, even if that means sinking a weight into the base.
The reason for the weight is simply to help prevent accidents, it is for the same reason that the upright one has been drawn with a larger base.