Attach the Legs
To attach the four table legs, cut four 6" triangular gussets from the remaining 3/4" plywood. Leg style will determine mounting method. For table shown, the top was wood glued to the top of the leg; a 3" #10 wood screw was driven down through the gusset into the leg. Mounting method must be secure enough to prevent the legs from racking while rolling. Some legs may already have a threaded rod in the top, which would be an excellent way to attach to the gusset. If the diameter is large enough, drive two screws into the tops of the legs.
Depending on mounting method, it may be easier to attach the gusset first. To attach the gusset, coat the two 6" edges with wood glue and install two 1 1/2" #8 wood screws through the 1x8 on each side.