I take it you mean wood? Whatever I can get my hands on basically, in enough quantities. So far I've found a source for maple, african mahogany, and northern ash at what seems to be a reasonable price, but I'm still trying to find a dedicated dealer of exotic timber and tonewoods.
Add me on msn - I won't be online much but it'll take me a while to get all the gear together, make the templates etc, so there should be a fair bit of time to discuss it. You can PM me here at the forum though, as I check forums every day or other day.