You will need a soldering iron and you will also need failsafes on the DIY models as well as the normal 10-15ampers. On the more expensive 15 and 30 amp ones they have a built in failsafe. When you add together the cost of a DIY 10amp and a failsafe it is cheeper just to buy the 15amper with built in failsafe.

For 4 motors you will need 30ampers though