Just build a typical 2C Mag mod and use 2xAA cells inside of C shell adapters. For decent throw, the stock smooth Mag reflector works well with a Seoul P4 LED.
I built one using a standard 2C Maglite, Badboy Nexgen 1000 boost driver from The Sandwich Shoppe, Litemania P4 CMag heat sink, Seoul P4 U2SWOH-bin LED from Photonfanatic, 2xEneloops, and 2 Eneloop C shell adapters. The setup also can run well on 2xC alkalines. I've measured about 19,000 lux at 1 meter and about 1.2A current draw at the tail.
If you want to build a AA Mini Maglite mod, the
mariposaoyako copper heat sink makes the mod very easy. Unfortunately, he is sold out of the heat sinks and has no plans for another run. I've built one of these, again using a Seoul P4 LED. Driver was a BBNG400 this time. I used a Fraen LP optic from The Shoppe, but the DX14598 18mm x 12mm reflector also works well. Tailcap switch was a Terralux TCS-1. But you can also retain the twisty switching by not using the heat sink's copper collar. When you screw down the bezel all the way, the copper heat sink is pushed downward, breaking the circuit and the light turns off. Unscrewing the bezel allows the spring pressure from the stock AA MM tailcap to push the heat sink upward, completing the circuit. If you go this route, I would roll a small o-ring over the heat sink threads so that the heat sink doesn't fall out of the MM tube when changing batteries.
You might be able to rig a work-alike Mini Mag heat sink using some copper or aluminum tubing, rod, and sheet from the hardware store. Get a 0.560" OD/0.510"ID tube (the OD is the critical measurement -- it has to be small enough to fit into the MM tube, but wide enough to fit the 14mm driver board). Thin walled tube is convenient (but not a show stopper) since the tall inductor on the 14mm BBNG driver from the Shoppe is fairly close to the edge of the driver board. If your ID is less than 0.510", you can just cut a clearance slot for the inductor. In fact, if you use an SOB driver, the inductor is right at the edge of the board and you will have to cut a clearance slot. The MAX4073 voltage sense amplifier IC pins are also fairly close to the board edge for both the BBNG and SOB drivers. Kapton tape can be used to insulate those from the metal heat sink. Cut an 0.560" diam disc of metal from the metal sheet and thermal glue it to an open end of the tube. Then cut the tube to a total height of about 0.242" (including the thickness of the metal disc that caps the end of the tube). Get some ~3/8" diam rod (has to fit through the top of the Mini Mag battery tube, which I measure at 0.410") and cut a piece 0.192" tall. Use more thermal glue to center and attach the rod to the tube at the capped end. Total height of the sink should be about 0.432"-0.433".
Drill and tap a small hole through the sheet metal cap and into the metal rod section. This will be the ground connection for the driver board. Also drill two holes through the sheet metal cap to run the LED+ and LED- wires that go from the driver to the LED that will be mounted on the top face of the metal rod section. The 3/8" (about 9.5mm) diam rod is wide enough to fully support a Seoul P4, which is 8mm in diam. The MM battery tube opening is 10.4mm diam, giving a clearance of about 0.45mm for the metal rod section. 26 gauge Teflon-jacketed wire is about 1mm diam. So, you will probably have to file two grooves about 0.5mm deep on each side of the metal rod section for the wires to clear the battery tube opening.
Edit: A key with this work-alike heat sink is that the sheet metal cap has to make good ground contact with the Mini Mag battery tube (at the top of the tube) and the driver's ground wire has to make good electrical contact to this metal cap.
