Built a minimag today and just thought I would share the results. I had a new red 2 aa minimag that was lying around and just never got used cause it is so dim. I have got about 25 bucks in the mod, so not really budget, but you could do it cheaper and get pretty good results. I used a 500ma micropuck from led supply, a 1c tint xpg on a 14mm star, a terralux tailswitch, and a carclo optic. Took a piece of 10 gauge wire, flattened it and trimmed to just under the ID of the battery tube. Arctic alumina epoxied it to one side of the micropuck. This slid up to the top of the ridge on the head end of the light and acted as the ground. Soldered my input ground wire to the piece of flattened 10 gauge. Took a flat round piece of metal and epoxied it to the other side and soldered the positive wire to it for my battery connection. Slid the micropuck in the tube and epoxied it in. Lightly sanded the top of the tube to remove anodizing and epoxied star to top of tube. A little trimming on the reflector and done. Light had ugly beam no matter where I sunk the led into the reflector, so ended up using a 20mm tight optic I had lying in the box. Light came out great, and is actually brighter than my RC-A4 with an R2 from shiningbeam for comparison.
Great way to actually make a minimag useful and still have it run on alkalines. I know this is useless without pics, but if anyone is interested in doing one, I could do another one with a bunch of pics if they need it.