With nothing more than some nylon bolts and nuts, some hot glue, and the required brass bolt, and maybe some PCB material for structure, you could make the knob stationary, and make the coil the thing that moves along a short track. Looks like a fun project! I've been wanting to build another DC RX, and the analog tuning is attractive. Maybe next winter. Too many projects lined up right now, one of which involves pistons, tires, and a winch.