Cornfed: You can just make a rectangle (like a picture frame) out of wood trim (or whatever) and place the tube inside so that it does not touch the sides. The top of the rectangle should also clear the bottom of the player. This is pretty much what the manufactured gizmos are like. I use a wheelbarrow tube, which is even smaller, on my two box mini sytem in the spare room. I recently tried it on my CAL player in the other system and preferred the vibrapod/platform sandwich instead. However, the tube sounds better (than the Pods) on the cheap system. I guess that you just have to try it and see if you like it. The tube muddled the mid bass and midrange on the CAL but had the opposite effect on the little system. The little system is thin walled and resonates (even after I damped it) and the CAL is built like a brick.
Sand bags under a cdp - didn't work well
Last night I started the process of vibration control with the use of sand bags (3) under my Arcam cdp. What I found was that while everything became more focused/detailed it also became more sharp/harsh/forward/aggressive. I didn't know what to expect but it certaintly wasn't this. Van Morrison's voice on trk #5 on Sailing to Philadelphia was abnormally aggressive and in the end I preferred the sound without the bags. Any thoughts as to why things became too sharp & aggressive????