You can salvage some nice motors out of optical drives but they can be tricky to control ... His test circuit uses six 2N2222 transistors to protect the Arduino from excessive current.

Seeing this Toshiba motor drive ... for pairing with an Arduino’ as it combines operation across 1.8 to 7V with up to 4A drive – so that is Li-ion batteries, 5V USB and 4xAA cells all covers, but ...