A start perhaps, in the absence of vibrating wand the new electro could be connected to his balls under the cage so it can't be removed. It is possible, I think, to power this just enough to stimulate his cock and make it harden uncomfortably in the cage. Now I'm trying to think up a task that has to be completed within a time frame set by Sir while sub is gagged and blindfolded. It needs to be a practical task that involves some pain/pleasure as each stage fails or succeeds. Hands cuffed behind, moving some items from one site to another (each side of the room?) and balancing them onto a pile. Lego bricks scattered, he'll feel them with his feet, collect one at a time and make a tower of them.  Say ten items? Each fail gets a shock. Dress code is rubber suit. Would it be too complicated to involve tit clamps as well, maybe each nip connected by a clamp and string to corresponding big toe and just short enough so he can't quite straighten his leg without a painful tug.