I am making my jet pack pretty damned accurate, and completely from scratch. For the missile, I could not find any parts that were close enough to the shapes needed. It is pretty easy to make your own custom cones. Roll up some plastic overhead projector paper into the exact cone angle you want, coat the inside with bondo, fiberglass resin, latex or whatever will dry to hold the shape. Cut the ends off to the desired diameter and that's it custom cones.