This picture is a Dual DC-/Stepper- Motor shield for Arduino. It is available on various sources for ca 5.- USD +/-. The Picture is borrowed from one of the shops on AliExpress.
The interesting thing about these monster chips is that they are full H-Bridges capable of working up to 40V with a 30A continuous output. The only drawback is that they are 5V design on signals, but we can add level shifters to deal with that. I have failed to find a 3.3V version. The trigger level is 3.25V so a 3.3V signal might work by accident thought.
The chip shown is VNH2SP30. You will find loads of notes and design on this chip on the net as they are very popular for good reasons. They also provide a very easy path to a straight forward 30A stepper motor.
The size of the chips are however actually larger than the total area I use on my own using discrete components, thought I only target 15A. But, as stated before you need to deliver the current to the motor as well. I actually want to buy one of these for testing.