Dan can you add the bounce tool from Universe sandbox to universe sandbox 2
That is actually under consideration. As others have mentioned, the planetary collision mode makes very little sense for anything but the largest objects. The reason "bounce" was there before, and is not now, is that the previous version used a third party physics engine which was actually _only_ supporting small scale collisions, whereas currently it is a custom engine, we built ourselves, which only supports the large scale.
Point being: we are seriously planning on implementing "bounce mode", but it is a different beast entirely, and it will likely not happen right away.