Go to Lowes or Home Depot and check out the kitchen counter tops. Usually they have slightly damaged one that you can get at a discount. A white counter with a small lip and rolled up back so nothing can roll off works great. Build a solid bench at least 36" high (or more) and just sit the counter on top of it. I also use a 4x8 folding table in the center of the room for assembly.

I like the cement floor as carpet and padding makes it hard to find things when you drop them.