The sandwich prior to routing. The bolts go through the jig holes in the blanks. The holes at the base of the flanges have been pre drilled while in the blocks for uniformity.
DANGER! DANGER Robinson Family! That flush trim bit is just waiting to eat the end of your finger off! Work the piece into the bit slowly. I wore heavy gloves to protect my hands if (when) the bit grabbed the piece and jerked it about. Wear a full face mask and long sleeves. The chips come off fast and hot. I put a cardboard box around three sides of the router table so I only had to clean up a small area instead of the whole shop. Oh, and earplugs were nice too!