Typically I go to digikey or mouser and do a search for a good fet. You find a good one and look at the datasheet and make a circuit on some copper clad pcb bread board. Do some searches on these things and you find what you need. One tip though. Go with a newer part, they create much less heat than older part #s. Learn to use SMT parts. They save LOTS of space.
The big chip here is an example of a surface mounted fet, but follow datasheet instructions.
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Here is another of the same ST fets on a tiny board controlling power to a bunch of other stuff.
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