actually an idea is that a 3d printer controller can be made up of 'co-operating' arduinos
some of the boards notably stm32f103 - blue pill - reaches $2 price point on ebay
(the benefit with this soc is that it is an arm cortex-m3 32bit mcu, it does USB natively on chip and runs at a pretty fast 72mhz)
and even more recently stm8s a 8 bit mcu - reaches $1 price point on ebay
could be programmed - 'arduino style'
http://www.stm32duino.com/
that sort of provides some motivation to meddle with them as stepper controllers as now with things like the blue pill, you could literally parse g-codes from a 3d printing file and control 2 motor for instance. hence, the job of running a 3d printer could be split up between 2-3 blue pills controlling separate motors and devices (e.g. a heated bed, monitor temperatures etc)
but this design would detour from the more common monolithic printer controllers design as it would require a co-ordinating host so that the 2-3 arduinos run the printer in sync