If you need (emphasis on need - if it's not in the requirements, don't bother!) to make it smaller, you can fold the low power/compute section underneath the power section by putting it on another board and using either a mezzanine connector or FPC/FFC/ribbon cable to connect them.
You can also integrate the motor controllers directly onto your PCB and give them a combined thermal solution i.e. one heatsink with one fan if needed.
But likely your effort is better spent on making the rest of the printer rather than this :)
If you need (emphasis on need - if it's not in the requirements, don't bother!) to make it smaller, you can fold the low power/compute section underneath the power section by putting it on another board and using either a mezzanine connector or FPC/FFC/ribbon cable to connect them.
You can also integrate the motor controllers directly onto your PCB and give them a combined thermal solution i.e. one heatsink with one fan if needed.
But likely your effort is better spent on making the rest of the printer rather than this :)