I use a removable plug in the plastic plunger that has a sharpened screw in the center. I can remove it and use a longer dowel turned for a snug fit into the plunger for longer length or I turn some items in halves where appropriate. The sharpened screw center allows me to turn a small dimple into the center of the base so it isn't difficult to turn it away on completion of assembly. Alternately, if I use a thin floating base that doesn't leave much to turn away, I'll glue a plug onto the first ring after it's attached to the base using another method for centering it. I then turn that plug away when the assembly is complete to expose the floating base. I suppose you could do that at any ring level and not use any sort of plunger extender by gluing in a bridge and turn a dimple or a hole. that way some of the potential "slop" in the assembly is reduced. I'm sure there must be other ways to "skin" this cat.