Regarding question #34 “Required bevel on carrier glass”
Most carriers have retainers that grip the 45-degree bevels of opposite edges of the glass. The retainers must generally be made so that they don’t quite reach the mating glass surfaces between the two plates. Otherwise the retainer would interfere with the opposite glass preventing the carrier from being fully closed and the interference could damage or even break the opposite glass. Too, if the retainer stuck up too far it might also bite the negative, ruining it.