Opensource Rocket nosecone, transitions and couplers... OpenSCAD sketches.
Just in case it's useful I decided I'd chuck a few bits of openSCAD code I use to generate 3d models of transitions and nosecones and couplers for rockets onto github. I am no amazing coder but it's nice to opensource what little I can! Its pretty well commented so you just stick in the dimensions you need and render! IT'S HERE!