At first I had the bright idea of using a light weight plastic baseball bat for a Payload Bay and Rocket Body (bad idea.) I got one from a Thrift Store that was the right size and shape, and only weighed about 4oz. Only problem was that I couldn't find any glue that would stick to it, so I abandoned that idea.
Next I started looking for a round Shipping Container for architectural drawings. It needed to be a minimum of 2.25 inches inside diameter (the width of the Cheap Digital Camera.) I have one at home that is 2.5 inch inside diameter, but it has 1/4 inch thick walls and it's too heavy; I need one about 1/8 inch thick walls. I found one at a FedEx Shipping Store in the local Wal-Mart. It was 3 inches inside diameter; a little bigger than I was looking for, but it'll do. Here I have the Motherboard mounted in the Payload Bay.