I wish I had a picture of it now, but I made a really cool CG checker out of 3/4 PVC.

The base was about 24" wide (across the wings) and 10" deep (nose to tail). On the sides of the base I put a T and some 16" verticals with a end cap. The plane's wing sits on the cap. When your all done If you don't glue the vertical's T will fold into a nice flat thing that you can stick anywhere.

Cost was like ummm $4


P.S.
Use the round PVC caps, not the square ones.