Any rules of thumb as to which parts fit what?

Hi please forgive me if this is not really answerable, but I would like to mod up a bright led light from cheap parts to make something great.
Where do I start?
Might there be a document or rules of thumb as to what fits what as far as switches bodies, or to say start with "this" cheap light and this switch will screw on etc..
I can do all of the electronics, but maybe some type of spreadsheet or like recipe of parts might be available. I hope I am making sense. Questions like, where would this driver board fit, into what light..
I just love all of the cheap parts available, maybe I just need to go in the garage and cut a pipe to battery length.
Thanks for any suggestions though. Current mod is energizer 1W rechargeable, direct drive alot brighter, about 1 amp draw. Awaiting Seoul z-power led from DX. Hope it solders in.
Steve

Hey, Steve - there are really no "rules of thumb" as far as what parts fit which lights. It really depends on the light you have. I'm not familiar with the insides of the light you have, so measure the insides and then browse through The Shoppe's selection and see what you can fit.

Also, your choice of LED emitter should match the optic/reflector size, which in turn has to fit inside the mod host, so things can turn into a balancing act to make everything fit and work OK.