Put the countertop on the base, put the MDF on top of the countertop, and line up the marks you drew on each end of the MDF with the countertop below it. When you have it lined up, clamp things down, and route the edge of the MDF using a 1-1/2" or longer flush-trim bit, with the depth adjusted so the bearing rides on the countertop. I clamped a couple of scraps of doubled MDF at each end to give the router base something extra to ride on at the ends.
Post Woodworking’s Hampton shed is a major standout in design. The sleek farmers porch immediately draws the eye into its pure New England charm and provides the utility of shade and a cool place to sit and enjoy a cold one. Like all of our sheds, the six-panel doors which add to the structure’s aesthetic come standard. They’re made out of fiberglass to last through many decades out in the elements.