Alternatively to the foam plug I decided to try out a 3D printed plug for increased accuracy of my 86mm Von Karman composite nose cone. Initially this was due to the fact I ran into some inaccuracy / concentricity difficulties of the finished wet lay up of the foam plug (which in hind sight was not related to the use of the foam plug). Furthermore it is interesting to explore the potential uses of a 3D printer in rocketry applications.
So I modeled a 2 part nose cone plug to be 3D printed and ordered it through www.3Dhubs.com for EUR 31,-. This 3D printed plug will be aligned butt-to-butt to the aluminium coupler and once the wet lay up is finished the outer shape of the nose cone, shoulder and outer diameter of the coupler will be machined in the lathe to final dimensions. The 3D printed part will remain in place, locked between the aluminium coupler and the composite nose cone. After a heads up from LD about the lack of concentricity by simply epoxying 3D printed parts together, I decided to make a M10 central spindle with center rings to keep all parts are aligned.