I have a plan with the help of james3, parts in the post
Looking at a Single XM-L2 on a 20mm board from him with a 17mm Qlite 3 amp driver driver
I can then turn down a ’block/pill/slug drop in to the head unit.
Machine a recess at the front end to mount the LED board, with a second recess at the back to press fit the driver board in to.
it will just be a really wide flood …Mule? is that the word?
the driver is stated as begin good for 4.5 volts, so 3 x AA is good.
Otherwise it would be 3 x lithium cells, so near 12 volt and then need a different driver.
No switch, so it will work the same as the original, screw down to make battery contact. May need to create a spring or similar buffer to help push the base of the driver cleanly off the battery positive, so the modes can be swapped, from High/ med low.
Not sure about that but time will tell.
heat exchange is going to be an issue too, but only time will tell on this