RAMPS compatible driver module based on DRV8818 by Dean Gouramanis:
DRV8818 Stepper Driver Module for 3D Printers
The goal of this project is to fit the DRV8818 driver circuit onto the standard 0.8″ X 0.6″ PCB size used in RAMPS 3D printers. DRV8825 drivers are a popular choice for desktop 3D printers, because they can provide up to 2.5 amps peak current. The DRV8818 is a similar IC capable of driving up to 3.5 amps, but the circuit is too large to fit on PCB using regular methods. Also, without a propper heatsink it will overheat.
Schematic, gerbers and mechanical CAD files are shared on GitHub: