A good option if there was no other way but I took the easy way out and ordered the 29mm tubes. It was hard enough to glue it all together without having a lateral splice down the length of the motor tube to deal with on the centering rings.I was going to suggest cutting down a larger tube to fit a 29mm motor. Add a wrap of cardstock or a wrap of fiberglass/epoxy to strengthen it. You could pull it off on that motor range.