I used a layer of glass and epoxy for the shim on my two-piece. It started out slightly oversize, then I filed and sanded it down to a close fit. Hardly any water ever gets inside. My ends on all my poles consist of a 3" delrin rod the same diameter as the tubing, with a couple inches of it turned to ID for a press fit. One inch extends out of the tubing, with a grade 8 3/8" bolt threaded in with a nut to hold a washer over the end of the delrin. I assemble the delrin, washer, nut, and bolt, and then grind the bolt head off, then press it into the tubing with a little plumber's goop. I like this setup so well that I've gone to putting the same end on my wood poles. I just assemble it all in a 6" length of tubing and fit that to the end of the wood with epoxy.