Collectors have sent me insulators in padded envelopes and inside them have been boxes, cardboard tubes and various stout containers. One collector sent me tolls withing some utility grade plastic pipe. Those all work, but I like to wrap an insulator so as to minimize movement. I recently was looking on line for some high density foam for packing. It is expensive and comes in quite large quantities. I decided to keep my eyes open while shopping and found rubber floor matts at Harbor Freight. For $10 I got a pack of four 24'x24" matts. It is a little thicker than ideal, but I could not find anything else even close to that cost.