Brief:
This is a scratchbuilt anti-zipper design with interchangeable MMT/fin assemblies.

Construction:
Main BT with payload and 3 fin design. Avast! It is anti-zipper and can change from a single motor t' a 3-motor cluster in only a minute! Uses a center rin' t' separate payload from chute compartment. Begad! Arrr! I needed t' add extra weight in payload for clustered assembly. Avast! Well, blow me down! Uses quick links, eye bolts, and tubular nylon for strength.

I used plywood for fins with through t' body assembly. Don't skip on glue--epoxy is better! After first launch just a little black on fins but no damage! Also, arrr, use nylon chute! Save yourself some aggravation. Ya scallywag! I got mine at NARAM 51 from Sunward but any good chute will do. Well, blow me down! Arrr! Biggest trick is t' mount your coupler in main body so can change out fin assemblies. Ya scallywag! Build all fin assemblies with baffles so you don't need wadding.

Flight:
I went for it on first attempt with 3 D12-5s. Avast! I wouldn't use any less o' delay. Ya scallywag! Begad! I had long shock cords! You connect one t' any eyebolt in main body with a quick link, shiver me timbers, add a piece o' tubular nylon two times longer than rocket, me bucko, me bucko, then another quick link (this one gets t' parachute), matey, and finally another short piece o' tubular nylon connect t' the eyebolt in your baffled MMT/fin assembly. Make sure you use plenty o' epoxy in motor mounts! You can extend life of insides by sprayin' chute compartment with fire resistant paint used on BBQ grills.

Summary:
Fun rocket t' launch! Use a Clip Whip, ya bilge rat, matey, as it's t' only way t' go. Ahoy! Biggest pro is quick and easy disconnect of different fin assemblies from 1 motor t' 3 engine cluster.

You might want t' make it a little longer than 2 feet t' avoid havin' t' add weight. Besides that, me bucko, thar's nay a thin' wrong with it! Makes life easy if you fly in different fields and a cluster too much for one but great at the other!