Hi and welcome. I actually have several thoughts!
Gotta say I am perplexed. "the direction the speakers are moving," what does that mean? Are you suggesting the very light cones of the speaker will have sufficient inertia to move a 50-lb metal stand? Your ears would be bleeding before they would even think about moving the stand. In fact probably the neighbor across the road and down two blocks, ears will be bleeding before that.
Do some research on the resonant frequency of various diameters and thicknesses of the tube you think might be good. The lowest audible frequency generally heard by the best of human ears is around 20Hz. I can't see many tubes getting that high unless they are 0.010"-walled spring steel.
It all sounds like a very complicated approach to sitting a couple of speakers on the floor.
Just what are you trying to achieve?
Do the stands go from floor to ceiling or what?