Whew! You had be concerned there for a few minutes, I have been known to do crazy, whacked out, unsavory and questionable things.
But on page 9 of the Destructions there is a bit about building a MM:
10) Scrounge up the motor mount tube [MM] and centering rings [CR]. Pick a centering ring [CR], any centering ring, and put a small notch in the outside edge as seen in (Figure- 14). The notch will allow the Kevlar shock cord (yellow cord) to be tied to the middle of the MM tube and be threaded up through the body tube [BT]. The centering ring [CR] with the notch will now and forever be your fore centering ring [CR], the one that will be closest to the nose of the rocket. The other centering ring [CR], now the aft CR, will be much relieved to learn it won’t be the victim of any cutting.
11) Measure and mark a line 7/8” from one end (now the aft or tail end so mark it as such) of the motor mount tube [MM], and 1” from the opposite end (now the fore or front end so mark it as such). Run a small bead of glue around each of the lines you just made and slide the fore centering ring [CR], the one with the notch, on to the fore end of the motor mount tube [MM] to the line you just made. Slide the aft centering ring [CR] on to the aft end of the motor mount tube [MM] to the line you just made. Keep the centering rings [CR] as close to 90 degrees to the motor mount tube as possible until the glue dries. (Figure- 15)
If your Destruction manual does not have this bit we will be very happy to ship you the missing text.
