Working on a tuned intake for a 250cc scooter engine. I have a good idea of how long it should be but wanted the option to try out different lengths to find the best results. The adaptor and bell mouth fit onto a length of aluminum tubing for testing. I didn't design in any clearance (or interference) and found that giving the printed part a quick dunk in some hot water expanded them enough to slip over the end of the pipe. After it cools the parts are pretty much one. Another quick dunk is enough to disassemble them.
haven't had a chance to get it on a dyno yet. I'll be trying 6 lengths in 10mm increments. If it does work I'll redesign the bell mouth and tubing as a single integrated part.