Summary

One aluminum 10 mm square pipe was used. The square pipe is excellent for distance in a straight line. The redesign was simply a hobby. A number of M3 screws are required for assembly.

I didn't like the pen folder, so I put it together with a different design, with M3 screws to hold the pen in place.
https://www.thingiverse.com/thing:4637226

I recommend this firmware because the Y axis is reversing the motor.
https://github.com/imaicom/GRBL-28byj-48/

This is an optional part that converts to a trapezoidal rail.
https://www.thingiverse.com/thing:4637909

https://denshiman.com/Arduino_mini_CNC_plotter.html
https://denshiman.com/cnc.html
https://denshiman.com/10mm_square_pipe.html

https://www.youtube.com/watch?v=Pyx6eILtui4