Ideally, they should look nice, of course, but the other properties that are good are:

1. waterproof or water resistant. (this is where wood is weak).
2. strong and shatterproof
3. relatively lightweight (solid brass = no good for this reason).
4. readily sourced
5. easy to work.

Now the rest is up to your imagination as far as materials and ideas go but to help get things "rolling", so to speak (no pun intended), here's one hint: