Level 3 certification is the gateway to the biggest motors M, N & O. The process for level 3 cert is complex and requires a lot of documentation and the guidance/approval of two TAP (technical advisor panel) members. I was very fortunate to get two awesome rocketeers as my TAPs: Jack Garibaldi and Kurt Gugisberg.
Jack must be photo resistant like myself, so I could only find a picture of one of his rockets:
Kurt frequently flies his cat Nibbles (plush animal that is):