Madcow 38mm motor retainer.

Just flight tested the product yesterday on a Wildman RB-05A Sport. It worked great in a flat bottom rocket application. An economical option for motor retainers at $11. Will work with a 54mm body tube but install was kinda hard to align holes precisely. Other than that thanks to Apogee for stocking it. This little product saves me from losing a $100 Aerotech complete casing. Fugly and old school but works.

Kudos for finding a solution to your problem, bonus points for going old school.