We start with a picture (Figure 3-4) of a CubeSat skeleton (ordered from Pumpkin) and a TubeSat skeleton (created using PCB specifications from InterOrbital Systems).
Figure 3-4. Again, our two variants of a picosatellite, with a quarter for scale
In terms of material, a CubeSat uses an open or closed metal case. You manufacture and attach your satellite PCBs and sensors with metal bolts. A 1U CubeSat will have a Base Plate Assembly, a Chassis Wall Assembly, and a Cover Plate Assembly.
A TubeSat reduces weight by using the satellite PCBs as the structural elements, separated by Teflon spacers.
Both CubeSats and TubeSats can be bought as preselected kits. Direct comparison is slightly nuanced. A Pumpkin CubeSat containing the skeleton and basic processor and I/O runs $7,500, with $5,500 or more additional for adapters and modules. A TubeSat kit (parts only, no launch) is $750 and includes the microprocessor and transceivers, but it does not include the PCBs; those you fabricate for perhaps $500 more.
For those of you in Europe, the CubeSatShop sells CubeSat skeletons for €2300. Clyde Space sells the ISIS 1U CubeSat for £2250. Back in the United States, Astrodev has CubeSat shells for $1250 and also lists transmitters, antennas, and other components.
Additional vendors appear about every two months, so at the time you are reading this, I hope you have multiple potential ...