Due to my recent interest in drawing robots I went and lasercut the parts for a plotclock. You can find the files and instructions on thingiverse
I cut it in MDF so its a little flimsy, the housing for the 2 servos controlling the arm wobble left and right. I intend to modify the design and then laser cut some new parts that minimise the wobble. For the eraser I turned a small block of chemiwood and drilled out a hole for the pen to sit in.