We are using model aeroplane 1/8" Birch plywood, (6 to 8 plies, I forget), for lift pin receptacle pads on the rear. Making them in the shape of a teardrop gives a nice handhold for fitting. The teardrop will be removed once properly fit.
Here Alan double sticky taped the shim to a T bar sanding tool. Made for easy, controllable sanding. Made for safe sanding to when using belt sander.
Note that Craft places sell Birch plywood from the same Mfg. that makes the model aeroplane stuff. If it says Craft on the label, it is probably only 3 plies. The Midwest stuff from craft places says on it "Not for aircraft".
Y10-10-10