The prototype built corresponds in general to the expectations in the sense of functionality. Some small questions arise about the consistency of the display and the pen raise/lower mechanism.
The line drawing algorithm was to our satisfactory. It's speed was more thatn enough, so a delay loop had to be inserted to not saturate the step motors.
Among possible improvements could be mentioned a better user interface. It's current version lacks all kinds of intuitiveness. The controlling software could be extended to manage arcs and other angular drawing modes.