Two-fold reason for my design. First, light trap is fuzzy velcro in two differing orientations. Second, it acts as a stop so the inner box doesn't slide out completely.

The inner box has the gasket attached to the back edge on the outside of the box. The outer box has the gasket attached to the front edge on the inside. In order to remove the inner box, the lens board must be detached, then the box slides inside the camera. tim