I have been contemplating a couple of new designs for a chassis holder.
One is based off the old turntable holder, and another one using wood & dowels.
The wood one is basically a piece of 5/4" (5 quarter) plywood or 1.25" x 12" solid board. Make sure the wood and dowels are VERY dry.
Tape a sheet of grid paper to the base, it and drill a hole every 1.5" on it, 1" deep.
The hole should be about 3/8- 1/2", depending on your dowel size.
(Now the bottom board can be larger or smaller, but I think the 12" size is about right for most AA5 radios and other chassis.)
I would cut a variety of dowels in different lengths, with 4" being the shortest, and the longest maybe 10". Glue a piece of rubber to the top end of each dowel.
Varnish the board and dowels. 2 coats minimum.
Now you can put the chassis upside down on the dowels, with the dowels resting on the top of the chassis (Under it actually).
When finished, your board will look like a Cribbage board, so to speak.
Your chassis is upside down and easy to work on, and the dowels (pegs) prevent it from falling over.
You can place the dowels where ever you want to miss IFT's, transformers, and the tuning capacitor, and they keep the transformer from putting too much weight on one side.
Yes, you can use different length pegs to properly support it. If you are lucky, you could even angle the chassis for ease of working on it, too.
(If you really get bored, paint squares on it and play checkers or chess on it too LOL.)
A larger version could be made to support TV chassis also. I would make that no less than 2' square though.