C3POHHH! is a basic 3FNC rocket with a few twists.  First it is designed to cluster 3 -18mm motors and will fly just fine on anything you can load into it.  

Second are the fin stiffeners.  I had a bunch of those "thrust-ring spacer tubes" that you used to get in some Estes kits that were basically an 18mm engine sized tube with a couple notches cut out of the ends.  I wanted to stiffen up the fin mounts on this rocket without the hassle of slicing the body tube for fin slots.  It was a co-incidence that the "Cherokee D" fins i had chosen for this project were just the right size for those spacer tubes to snug up with on the body tube and I had 6 of them!

As you can see from the photos, it looks pretty cool (sort of like booster engines i thought) but the flight characteristics of this rocket are what really surprised me!  C3POHHH! has got to be one of the most stable, draggy rockets I have eveer flown!  With 3 Estes C6-5s loaded in, all up flight line weight is still only around 8 oz.  Yet, the highest flight I have ever gotten out of it was just shy of 1000 feet!  That equates to a drag co-efficient of like .96 which is insane!  With 3 Cs you would expect to see more like 1600-1800 feet with no problem but the fin stiffeners while acting like small tube-fins DO stabilize things for a very strait, smooth, rotation free flight, they also tend to slow things way down.  Just another example of the cool science stuff you learn in this hobby!