3/8" dowel. It easiest to glue together without this dowel, and then drill and glue in the dowel from the front face after the glue has dried.
1/4" screw, 2" long.
5/16" (M8) bolt, 2" (50 mm) long
Fence locking knob. l*$1ake from 3/4" baltic birch plywood using provided template. Drill a hole fiat to fiat size of bolt and chisel to a hexagon 1.5" (40 mm) "fender washer"