3D Printer Made from old CD Drives

Firstly, my apologies for the quality - this video was quickly shot and uploaded on an old busted Android phone. The whistling noise is from the mic, not the printer. Secondly, credit where credit is due. I got the idea by watching Tinkernut's video: https://www.youtube.com/watch?v=anIy6eb1fW0 Now, about the build (if you are considering taking on this project yourself): Even though the printer needs 3 CD drives, I ended up needing 6. Why? I broke 2 trying to drill mounting holes in the moving carriage, and the 3rd one had it's laser travel moving at a 45-degree angle, not straight up and down. Also, it's motor was a regular DC motor, not a stepper, so it was useless. The moving laser carriages have little plastic parts that mesh with the screw shaft attached to each stepper motor. These plastic parts have purposely thin areas to prevent binding and allow it to flex, causing the carriage to remain stationary while the motor spins (equally as catastrophic as "missed steps") To avoid this, I plugged up these areas with hot glue so that the plastic was less flexible, keeping the mechanism meshed with the screw shaft. This needs to be done, because the compound X- and Z-axes AND the printing pen become very heavy for these little stepper motors to move, and they WILL start grinding. Finally, I had to clip rubber bands on the back simply to counter the weight of the moving parts on the upper half, as mentioned above. I'm using an imitation Arduino Uno (Elegoo) and 3 imitation A4988 stepper drivers (also Elegoo). The Arduino is flashed with GRBL and I use GRBL controller to home the motors by hand and parse the g-code files. I am NOT using actual 3D printer firmware because of the on/off nature of the pen. 3D printers control the extrusion of the filament by yet another stepper motor, which is controlled via g-code commands generated by slicing programs. Since this pen can only be switched either on or off, I wrote a python script that will parse through a gcode file, search for Extruder commands, and convert them to spindle-on or spindle-off commands. While GRBL cannot read Extruder commands, it can read spindle commands (since it is designed solely for CNC machines) so I used the digital output of the spindle pin (pin 12) on the arduino to control a transistor which switches the pen on and off (as can be seen in the Tinkernut video). Lastly, I use Slic3r as my slicing program (and I use Anim8or as my free modeling software... I've been using it for years anyway) and I spend HOURS tweaking the filament and speed settings in Slic3r to get the best quality I possibly could. It is worth noting that you can use Slic3r to add custom gcode during certain events, i.e., the very start of printing, and in the latest version of Slic3r, before a layer/z change and after a layer/z change, so again, I put in more spindle commands here to turn the pen off and back on again in between layers. I also used the "dwell" gcode command "G4 P1" around my spindle commands, since my 3D pen has a little auto-retract feature when you release the button. To give the pen time to retract the filament, and then time before it starts extruding again, using the "dwell" command is very helpful. Thanks for watching! Happy to answer any questions!