Hey Brian
I havn't made any, but we had an island once that had bean drawers. The drawer front was typical 5 pc. with a plexiglass panel. The drawer sides were attached to the front with a half blind dovetail joint, the sides being inset 1/2\" to hide the slides. Approximately 1-1 1/4 inch behind the drawer front, a dado was cut in the drawer side from top to bottom to allow a panel to slide in creating the pocket for the beans. This was an inset drawer, not an overlay. They used side mount full extensions. If I were gonna build one, I'd use pretty much the same method, except I'd use tandems, flush the sides to the drawer front, and set the slides behind the inside edge of the face frame enough to give me a 3/32\" clearance between FF and drawer side. But that's just me, I'm not exactly sure how I'd set up an overlay application. The piece we had looked like a piece of furniture, rather than a cabinet. From your design it looks like you may be going for that look also.
That's about the way I was thinking of building them. Maybe a 4 sided dovetail box. Cut out the front of the db leaving about 1\" to screw into the DF. Once filled, the cut edges won't be seen.