I am big lover of the Raspberry pi 2 and there is an even better pi 3 now out.
I have just seen an add on controller board for it called a Gertbot. Two can be cascaded together to run 4 stepper motors.
[
www.gertbot.com]
[
uk.rs-online.com]
I immediately thought of 3d printing. I have not seen a pi running the controller side, only the host software.
It uses 64 MHz ARM Cortex-M3 processor. Can Repetier firmware be made to run on it?
The pi could then run both the host software and the controller with its own LCD.