I want a flat aluminum or polymer housing with three separate AAA battery compartments side-by-side that will each accept an ARC AAA head (picture a Zippo shape with three ARC AAA heads).
I also want a belt-clip on one side to attach it to my pocket or my hat (in three-LED headlamp mode). Stainless pocket clips are available from knifemaking supply stores.
I already own three ARC AAAs. I'd pay another $30 for this accessory, maybe more . . .
What you're asking for is pretty tough to make, since it can't be made on the lathe. If I were you, I'd epoxy my three Arcs together, screw a pocket clip into the middle lanyard hole and call it a day.
What you want could certainly be made on a CNC mill, but it will be way more involved than something round and threaded.
Dilettante, I could make this for you, as I have made a tap for the Arc heads already. I can save Dan the trouble of making one, and let him concentrate on the lathe stuff.
This sounds like an interesting project, please contact me off list. I even have a clip available...
Dspeck, I just sent you e-mail. Right now I just hold three of them together with a piece of inner tube and use a Zippo money clip to clip them to my hat. Not fancy, but it works.