I just got a beta version of Art Applewhite's Max-Q saucer-like object. This sports a swappable motor mount with 1 x 29mm, 2 x 24mm, 4 x 18mm and 7 x 13mm options. Even thought the cat is basically out of the bag on this rocket, I was asked not to review it yet. So, I won't provide photos of the parts or intermediate steps. I'll post a shot of the finished result.