Brief:
I built CORONAry from a plastic cigar tube once occupied by a Garcia-Vega English Corona (hence, "CORONAry"). It is a tumble recovery tube fin design for 13mm motors. It utilizes a somewhat different method for inducing "tumble" after motor ejection, in view of the inherent stability of tube fin rockets -- CG aft of Cp is just about impossible.

Construction:
Construction is easily inferred from the photos -- six 1/2" long tube fins are cut from one cigar tube with a razor saw, and attached to the base of a second cigar tube using 5 minute epoxy. The plastic has to be "roughed" with sandpaper, or the epoxy won't adhere well to it. A small Estes launch lug is added as shown, using a wooden match stick as a stand-off, so the launch wire clears the tube fins (photo). And that's it -- there is no motor tube; the 13mm motor is friction fitted by wrapping with a long piece of masking tape (it takes about 28" worth). Two 1/4" holes are drilled 1" from the top of the cigar tube to allow ejection gases to vent sideways and impart a rapid spinning motion to CORONAry at apogee. If you don't do this, CORONAry won't tumble at all, just drops ballistic like a badminton shuttlecock -- its not that big of a deal, since the rocket is so light, but the wobble prevents too much speed building up as it falls. I left my CORONAry in "natural" Garcia-Vega sandy-tan finish, but I am going to rethink this, considering our sandlot launch site by a San Diego beach area. Bright colors would be better, if you want to get it back.

Flight:
First flight was on a 1/2 A3-4T. Great fast boost, straight up. Motor came popping out, and CORONAry tumbled about twice at 300', straightened out, and came in slow but ballistic 20 feet from the pad. It managed to score a direct hit on the only rock in sight (about golf-ball size) and all 6 tube fins popped off. That's why I added the vent holes to give it some wobble and slow acceleration on the way down. I have now flown CORONAry on A3-4T and A10-3 motors with similar performance; the tube fins stay on, but then I haven't hit anymore rocks with it, either. I have tried 18mm motors as well, since they fit the cigar tube perfectly without needing any tape; however, they are too heavy -- on a B6-2, CORONAry immediately went unstable, and tumbled on the way up as well as on the way down.

Summary:
PRO -- What's the point of CORONAry? Well, it provides a route to a cost-free little rocket (cost-free after you've smoked the cigar, that is) that is well-suited to the likelihood of losing these little guys eventually. It would make a good contest rocket for kids to build and fly, the tobacco angle notwithstanding -- see politically incorrect photo. If you get bored with CORONAry, you could use it for a badminton shuttlecock.

CON -- Well, the tobacco motif is there, but you can get rid of that by removing the cigar ring, sanding off the Garcia-Vega logo. You do need to paint it a bright color if you fly over sand. CORONAry will cost you $2.90 each to build if you don't smoke the 2 nasty little cigars that came with the 2 cigar tubes (thus making them "free"). But even if you do throw out the cigars, $2.90 is still cheaper than any rocket kit you can buy. In either case, you're on your way to a CORONAry.