On their 17 mirrors, Coulter also uses large pipe clamps over the tape. Others use silicon sealer as a backing. In some cases, the three adjustment screws bear directly against the back of the board. Surprisingly, this minimalist approach does work, though it s not easy to remove the mirror for cleaning, nor is it easy to collimate the scope. The three screws that are used to adjust the mirror during collimation require a stop of some sort to hold the mirror in the collimated position.
Many commercial telescopes come with two sets of three screws.
One set moves the back of the cell for collimation. The other set bears against the back of the cell. This second set is first loosened, then tightened once collimation is completed. I prefer spring-mounted screws as shown in the following diagram. The springs eliminate the bother of adjusting two sets of screws.