I bought 3 BT151-800R for 30DKR ~ $6 (USD) so I'll just use them.

I have a lot of different MOSFETs but they are low voltage (20-30V) and high power (80-150A) so because of the low voltage, they are not suitable.

Bigboat, I also bought the Velleman FLPS, and got it disassembled but I can't figure out how to wind 400 winds of 0.25mm (AWG30) copperwire onto the plastic holder.

According to my calculations and measurements on the plastic holder, there is only room for 365 windings on 3 "sections" and the last section is used for the 0.5mm (AWG24) wire, and I tried to wind 20 windings with AWG24 and it can barely fit.

How did you wind it? Did you remove the wall seperating the sections to get more room for windings?