I'm building shaker kitchen cabs with applied end panels. I've built cabs with finished end panels before but always with the end panel as part of the cab. This time around I tried something new: I built the box from 3/4" maple ply, all sides. On the end where the panel is to be applied, I ran two 1/4" grooves down the 1.5" stile in such a way that the plywood box side is flush with the frame inside edge, leaving the outer remaining 3/4" of faceframe with an exposed groove to attach the separately build end panel. I routed a tongue onto the front edge of the end panel and glued/clamped it to the FF, using screws to secure it from the back of the box. I don't 'splain things so clearly alla time so here's a couple of pics.
This method is pretty simple and yields a nice looking end panel, but it does leave the faceframe edge exposed, appearing to be part of the end panel stile. I'm looking forward to attempting a mitered applied end panel on a future project....much cleaner look but wrought with risk (DAMHIKT)