I designed these pieces to turn a 30mm cardboard tube I had laying around into a true model rocket that accepts 29mm motors. This works perfectly with the cardboard tubes from a Reynolds Wrap aluminum foil roll. I first fiberglassed the cardboard tube with 1 layer of fiberglass and epoxy, to make it stronger. Fiberglassing wasn't a necessary step, but will produce a stronger rocket. This also made the tube slightly wider but that difference is so small it should not matter. I slightly undersized the OD of the parts so it will work with either fiberglassed or non-fiberglassed tubes. My tube measured approx 28.6mm inner diameter. I highly recommend using a raft for both prints. Both objects should be printed upright with a raft. This means the nosecone should be printed pointing up with a raft under its bottom. The tailfin should also be printed upright with a raft to minimize lifting. Even with the raft I still unfortunately experienced some lift, but it was not enough to mess up the print. Once finsihed, just remove the rafts, and slide into the tube. It should be a tight fit, with a small amount of resistance. The tailfin should be epoxied in place. The nosecone should be attached using a shock cord. Created on SolidWorks.