The part should be made in two pieces; a flat plate that has the three terminals on it and a hollow back. It should be made the same shape and dimensions as the original battery as both the battery hold-down clip and the door have to be properly closed or engaged when the eliminator is in place.
The terminal plate (front) should be cut fairly thick and then relieved around the edge so that the hollowed out back can fit snugly over it.
The three terminals are positive, T and negative. The T terminal on the original battery is a thermistor between the T and the negative terminal. At room temperature it should read around 10K ohms, so we'll replace the thermistor with a 10K resistor.
The terminals themselves are snipped from .010 brass shim stock. These are very easy to solder to and are flexible enough to go around a few bends.
The terminal plate needs some machining. In the proper place mill in some .020 deep reliefs in the front of the plate. Take these in about 1/2" from the end. Then mill away the end of the plate inside your relief cuts, deep enough so that there is enough room for your .010 shim stock to fit between the hollow back and the terminal plate when the two halves are mated together. Not too deep though, we want the shim stock held in place if possible. Lastly, mill in some slots at the end of the relief cuts towards the centre of the plate.
The back, after hollowing, needs to have a hole drilled in it inthe proper place for the wire to come out. When you're done forming the case, place it in the camera and mark the back where the slot in the camera for the AC adapter wire is.
Once you've got both pieces made, put them together and mill the slot down down each side. The original battery has this slot to locate it when it is in place. You'll need to put it in.
Now cut your terminal out of the shim stock. You can cut them very accurately with a good pair of scissors. Lay a good dollop of solder on one end of each terminal then solder your wires to the terminal strip. Now 'thread' the terminal strips through the slots, up the relief cuts and bend them over. Use some hot-glue to locate and hold the solder ends to your terminal plate if you wish. Then solder the 10K resistor between the centre terminal and the negative terminal.
Put the two halves together (glue if necessary) and you're done. You just need a plug on the other end of the wire to match your power supply's jack.
That's about it. Now you can power your camera for hours with no worry about the battery dying mid-exposure.
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