It probably doesn't look like it in the pictures but I am using aircraft ply with basswood mounts on the servo tray. I think it's 1/8", but I'm not sure.
If you notice in the picture I had to prop the front of my GP balancing machine up so it would clear the top wing. I balanced my first couple planes with my fingers & had a hairy maiden on my SSE & bought the CG machine. I was almost an inch off from where I thought it was, so I'm a devout CG machine user now.
