Would there be enough space inside the case for the module with the batteries
and the switch mechanism?
Not sure where the switch could be placed, it would have to line up with the stem, is the case deep enough to allow it to sit on top of the module? Is this why you mentioned the importance of the battery position - top and bottom rather than side by side?
How would you envisage it all fitting together?
I assume that the batteries could be made to just contact the case back.
Starting with an LED module that has a tip function might be advisable
Great idea! I have a spare Gillette reflex module which has the tip wrist feature and just the single command button. It's in a very ordinary looking case, I've had it a couple of years and was keeping it just in case I ever needed a spare, would be excellent if I could put it to good use but I'm not sure how the batteries are orientated....I think they are side by side but I shall check it out.
Ed you mentioned that you had tried a LED module from a Rotary watch are you having a go at this Frankenstein - it would be great to see the photo's if you are.