Don't know the dimensions you are working with within the AAA head either, but here is what I have come up with so far looking for something similar to work with in the ARC AA head.
Measurements of the "pill" I removed from the AA head, if this helps any:
.390"/9.91mm at the anode/PCB end
.375"/9.53mm at the LED end
.320"/8.13mm deep, not including the anode solder blob contact, a portion of which extends beyond the main body of the head, being held in place by the "crimp" ring.
Of course this space is amenable to some adjustments :devil:.
http://www.leddynamics.com/LuxDrive/micropuck.php very small, this is what lives inside an EverLED "bulb, but most likely too big even after the encapsulating material is removed
The next two are most probably the same thing offered over on DX, but there is a less irritating 3 mode version available on Kai that I didn't see on DX's site:
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=3254 3 Modes
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=3255 Multi-(make-me-crazy) Modes
Both are a bit long for my space, but I ordered a couple to see if they might be coaxed into working out anyway. Just bull-headed that way I guess …
There was ARCMania's Micro Converter, but I believe that has been discontinued, but you might be interested in this:
http://www.customlightfactory.com/phpBB2/viewtopic.php?t=420