This is a drop in replacement for all of the stepper controllers for reprap/makerbot. It uses four Pololu 1201 stepper control modules so you can select your microstepping level from full step thorugh 1/16 step for each axis. It uses a 40-pin connector on the stepper board and 10-pin IDCs on the other end so it will work with gen3 motherboards. 6-pin IDC connectors are an option to use it with Gen4 motherboards in the future. Endstops are supported with CDROM style connectors for all four axis so you can use mechanical endstops when they become available. The fourth axis has a 4-pin header (GND/Ena/Step/Dir) breakout for easy connections to the Extruder Controller for stepper extruder use. It can be mounted using the same holes as current stepper controllers on a makerbot.

It is all through hole soldering for easy assembly.

Full assembly instructions are available at http://www.johnyang.com/p4ac

A BOM is also available at the above link