3 string Triotune - ukulele-like instrument version 4

This is a remake of my 3 string instrument. It is very similar to a soprano ukulele, minus one string. This is designed to be modular, so you can swap out parts to fit your needs. There are three necks to choose from and several bodies to choose from. I've also included some alternate sound hole designs. Feel free to modify and remix this project. Criticisms and suggestions are welcome.

This version is not fully compatible with V3 due to using a thicker 6mm x 300mm rod.

Here are some quick sound demos:

Quick song demo - https://soundcloud.com/grhmhome-583373264/3d-printed-3-string-guitar-sun-and-moon-sound-hole-design-with-rounded-body-test-001

Twinkle Twinkle Little Star - https://soundcloud.com/grhmhome-583373264/3-string-twinkle-twinkle-little-star?fbclid=IwAR0l3fv1M2tfMGPed6PyeJ6hnNsSpEfmHZ0QKn4wtdqRwd_FpYchtdJPVxY

Parts needed: 

Soprano ukulele strings or similarly sized strings.
You need a M4x20 bolt and a M3x16 bolt. One for the side of the neck and the other bolt for the back of the neck.
6mm x 300 mm steel rod
You will also need 4 - M1.7x6 self tapping screws. Two for the nut and two for the bridge. More if your geared tuning pegs don't come with screws.
Generic geared tuners for ukuleles. You will only need three out of the 4.    

How to assemble: 

Insert the nut near top of the neck at the headstock. There should be two screw holes. Screw the nut into place and do the same for the bridge. You want the flat side of the bridge facing the sound hole. Slot the neck and body together.

Connect both the neck and body. Make sure your tolerances are correct or things might break.

Insert steel rod from the neck into the body. Be careful and make sure the rod will fit in both the neck and body. Having a properly calibrated 3D printer is key. You do not want to break the instrument or harm yourself, especially if the tolerances for your printer are incorrect. 
 
Screw both bolts into the instrument.
 
For the headstock, you will want to have one geared tuning peg on the left side, one on the center, and one on the right side. Make sure the tuning pegs don't bump against each other or you will have a more difficult time tuning. You can use a small screwdriver to help make pilot holes. Again, be careful. Screw in the tuning pegs, one at a time.
 
After you are done, you can start stringing your instrument. If you are using ukulele strings, the strings may take a while to stay in tune, but that is normal for ukulele strings.

Credits: Berkbig77 for helping me figure out fret spacing.