SCIGS,
Nice job on the build and finishing! That thing looks great!
If you want to make your own foam discs to help cushion stuff in the payload bay, it is really pretty easy. Find a tubular object (rolled notebook paper will do if you can't find anything else; you can also usually find brass and aluminum tubing in a variety of diameters at your local hobby or hardware stores. Make or find a tube that is 5 to 10 percent bigger in diameter than your payload bay (in other words, just a teeny bit bigger so you cut foam plugs that are a little oversize). If you use rolled paper, keep it round and soak the edges with CA; after the CA cures, gently sand the edge to sharpen it. (Or, use a rat-tail metal file to sharpen the metal tubing on the inside, all the way around one end.) Use your cutter tube by gently turning it while you push it into some foam rubber.
Cut your foam plugs from a sheet 1/4 to 1/2 inch thick and you shoud have pretty good cushions for anything you load inside the payload bay. If that is not enough protection, cut another pair and slip them in on top of the first set of cushions. If you cut them slightly oversize in diameter, the friction fit should hold them in place.