Remixed to add cover and allow for Wantai Motor 42BYGHW811 (available off of ebay for around $10.00 Canadian, shipping extra. Will also work with OpenBuilds nema 17 motor (at time of creation of this entry).
Four pieces from JuanGg's original have been modified. This allows for a nema 17 stepper motor with up to a 48 mm body length to be used instead of being limited to a stepper motor with a maximum 31 mm body length. I had four already. I also modified the "switch support plate."
Four cover pieces have been added. The front and rear cover plate could be replaced with 2 mm thick acrylic plate.
Possible modification I can think of.
The stepper motors are on opposite ends of this plotter. I think it could be modified to put the x axis motor on the same end as the y axis motor. If the end stop switch is also moved, there would not be be any cables running from the left end of the plotter to the right end of the plotter. This would also allow easier upgrading from one paper width to another.
It may be possible to add a rotary cutter to the x axis that could be enabled independent of the pen allowing for continuous roll paper to be automatically cut after printing. Paper roll handling is likely not going to be trivial.
The pen could be replaced with a readily available injet print head allowing for an "opensource" printer to be created.
The media handling could be modified to allow using standard single or double sided PCB blanks to be used. For this, the pen could be replaced with either a "sharpie(tm)" to trace out etch resist on the board, or perhaps an appropriately coloured laser for photosensitive boards to be used. In the later case, this would allow for photosensitive solder mask and "silk screen" materials to also be used.