I use a two pieces of 3/4" finish ply held at right angles with some corner brackets from Lowes. Used 10/32 bolts and nylock nuts to hold it all together. This way, I can swith out the vertical "firewall" piece for ones with holes to accomodate different engine mounts. Plenty solid. When I want to use it, I bolt it to the top of a good sized Kobalt toolbox that I use for a flight box. Bent up a few small pieces of sheet metal for throttle servo / ignition unit brackets. The battery and all the other junk inside is plenty of weight to keep my Evolution 35 from moving it around. Sorry no pics, can't find my camera.

-J