Nice project 
please create this, it is needed for crate marking at logistics with big letters to read from far away.
(current tools are only small printers.or they use stencil cutters at paper and spray can.)
it have a servo for pen up/down.
2 stepping motor, one for drive, one for pen slide.
a Raspberry Pi in the box with wlan/bt for a Companion App.
the 2 handles to hold it on the wall.