LEGOing

I’ve never done much of this (LEGOing) or putting different parts together but I’m sure some of you have. Maybe you could post what you have found by trial and error works.
I happen to have two Ultrafire BJ08A lights. This is a single AA/14500 cylindrical shaped light. Just to see what would happen tonight I took the tail cap off one and the head off the other one and used the body of one as an extension tube and it works.
I’m not going to leave it in that configuration but it does work now as a 2 AA sized light.
Not too long ago I found out that the tail cap from my Smallsun ZY-C10-S fits on an Aurora single 18650 light that I have (which I’ve modified as an aspherical thrower). I also found that the lens and bezel assembly works well with that Aurora light as long as I use some epoxy so not an example of LEGO but still a useful combination (for me).
Buying two of the UF-BJO8A has ended up being a good decision for me. It’s very well build, easy to mod and I’ve ended up mixing and match the parts after the great bake off experiment as well as for other purposes.
One now has an aspheric (19mm) and the other is diffused.
What have you found that LEGO’s well among the lights that you have?