I’ve done this dc 12v out wires. I’ve kept the ac power so I solder bridged the exposed wires in my Mac mini (just 4+,1nc, 4- groupings not 20 wires). I drilled two holes in the front near the ir and power led for the two wires to come out. The power ac unit plug become loose so I had to wrap cello tape around the plug to stop it dropping loose. this is eight years old Mac, but my last hold on to this operating system I spent several years coding on. Macs too expensive and I’m going focusing on software available on Pc , unity, fusion360 etc.