Incredibly easy to build. But I recommend this for all skill levels. Easy pop and go staging that works great. I bought a second kit and made a 3 stage version. I was surprised that it string spin tested stable configured for flight without modification. The CG was just below the leading edge of the top stage fin. I used a A8-0,A8-0,A8-5 engine combination. It did not need any added weight in the payload bay. Although in actual flight I put an Estes altimeter in there. I do not plan to use any heavier engines as I do not like to lose rockets. Also I would not use any heavier engines without doing a string stability test. It flew wonderfully strait. The wind was calm and I would not fly it with wind as a 3 stager due of concern for multistage weathercocking. I put a small piece of tape as a shim to provide a very small amount of friction at the staging coupler as suggested in the instructions. I put an emptied out used D engine casing over the launch rod for the rocket to set on for liftoff. This is a great rocket as a 1,2 or 3 stager.
