Serving trays have been in use for probably hundreds of years, and wood seems to be the favourite choice of material for this particular project. I have built few of those out of wood scraps I had around the shop and this is the best idea so far. The trays (apart from specifically ordered) can be made out of plenty of pieces that otherwise would have not much use.
Some more expensive trays have all sorts of inserts in the central part, like tiles, metal sheet, or glass in it. Takes a bit more work to build them, but the effect is well worth the effort.
A cool idea is a tray (especially for a restaurant) with black chalkboard as a central piece. You can serve stuff on it and write right on the tray, nice.