For myself, after a lot of DIY which includes hardwoods, brass, brass balls, some magnets, oak platforms, Barry Controls vibration control (look them up) and then finally trying Herbies products, and then IsoAcoustics, I've come to the conclusion that while DIY can be fun, it just is not as fruitful as what the experts offer. When you add up the money spent on DIY experiments, at this point I think it's better to bite the bullet and get IsoAcoustics. Rubber pads will not cut it.
Ric Shultz offers some tweak suggestions and he knows what he's talking about. (IMO)