I finished one about a month ago, but I haven't flown it yet. It's a 3d printed rocket made with PETG. It's an 18mm min-diameter design that stands 15" tall and weighs about 2.5oz (motor not included). I planned on flying it on a C6-5, but smaller motors should work too. The motor's friction fit with a little bit of tape. Recovery is a streamer & rubber band style shock cord.
I made it in three main parts: the fins & lower body, upper body, and nosecone. It has 7 fins and they're all portions of heptagons. The outer cross section of the body is a heptagon. I first made a 7-sided Von Karman nosecone, but after reviewing the rules, I remade it as a 7-sided conical so that it'd stay flat sided. The lower body was printed with the fins attached. The lower & upper body were glued together with a 3d printed coupler and epoxy. To get a good separation of the nosecone, I sanded the inside of the body tube and the outside of another 3d printed coupler. There's a 3d printed motor thrust ring that's epoxied in place inside the lower body. The launch rod guide is 3d printed on the lower body.
Here are time lapse videos of each of the main parts being printed:
Here's the lower body & fins right off the printer:
Here's the finished rocket:
I planned on flying it at our club's last high power launch, but I kept busy with my bigger rockets instead.
I'll try to fly it in about 3 weeks at the next high power launch day.
EDIT: Here's the ork file: View attachment Heptagon Rocket.ork