the ULN2803 is an eightfold driver that allows to control up to 500 my / 50 V (max) by road from 8-bit logical 'classic' (TTL).

By connecting it to an Arduino board, this can help you afford to fly 8 outputs 500mA / 50V max.

Example of realization

Cockpit of a stepper motor 4 phases with a ULN2803