Mostly 3d printed pen plotter

This is a pen plotter which uses as many 3d printed parts as possible.
Any feedback would be appreciated!

List of non-3dprinted parts:
2X 2byj-28 stepper motors
1X Arduino mega 2560
1X Ramps 1.4 shield
2X Microswitches
14X Screws(the diameter of the screws can be deduced from the step file)
Wires
4X Nuts
2X A4988 stepper motor drivers
2X Microswitches
1X SG90 servo motor
1X Marker
1X Jumper

The rar files contain the modified marlin frimware and some gcode that I have tested.
There is a wiring diagram(sorry for the quality, pretty circuits are hard to make). Don't put any jumpers on the driver slots, or the motors will overheat. The gray line between the 2 pins is a jumper that you need to place for the servo to work