He's been experimenting with clamps, he has one for the fretless guitar section of the guitar-ukulele.
As for the electric quadro- or octo-bass the variables you can tweak are:
* length
* mass/length
* tension
There's some limit to how long you make the strings or you can't play it or otherwise you need something to extend your reach like the levers on the octobass. The other two are inside a square root which is not in your favor. Probably the easy thing to do is find some really heavy strings for a normal bass and see how low you can get the tension.
But really he's the one to build things. Back when I was in physics they kept trying to get me to do experiment rather than theory, if I have any regret it is that if I had studied experiment I'd be able to build all the things that my son wanted to build but, hey, he can build those things now.
Life is the ultimate test. We see ourselves reflected in the eyes of others. There may be nothing more humbling than being confronted with our own ignorance, except when we have an audience.
I guess once the strings are too loose, then they can’t vibrate consistently enough for long enough to be tunable/playable? I am wondering if a kind of lap guitar or a guitar laid flat might allow for pedals to be used that could bisect the strings to do octave changes upward in pitch. Going downward in pitch from an open position is going to be hard unless you have some excess tunable string beyond the last point of contact with the strings, and that contact could be released to increase the string length?.
You might be able to find an 8 string bass, and have two different string gauges. The top four could be heavier gauge and tuned at a lower octave. Or you could alternate gauges and silence the strings? I don’t know much about playing technique, but it sounds like it might be hard to build in such a way so idiomatic playing technique and style is preserved, but many alternate tuning methods and tools do affect how the guitar is played, so that may not be such a big deal if he’s the only one playing it, but if he wants the mechanics to translate to playing other guitars, those concerns might be more relevant.
It might also be possible to teach him how to build simple guitar pedals, which can easily pitch bend in post-processing once you know how the parts fit conceptually together.
Your guitar projects sound interesting and would be a good post for HN if you can find the time.
Get him a multiscale/fanned fret 5 string bass and just size up the gauges. A 37" scale bass trying to hit E0 will need about 0.18ga on the low string to be playable, which will definitely require a nut modification, but is doable.
There was once a company making a bass ukulele with inch-thick polymer strings. Playing them was kind of hilarious, and would be fun to see it scaled up to the size of an actual bass guitar... Probably someone has done it...
As for the electric quadro- or octo-bass the variables you can tweak are:
There's some limit to how long you make the strings or you can't play it or otherwise you need something to extend your reach like the levers on the octobass. The other two are inside a square root which is not in your favor. Probably the easy thing to do is find some really heavy strings for a normal bass and see how low you can get the tension.But really he's the one to build things. Back when I was in physics they kept trying to get me to do experiment rather than theory, if I have any regret it is that if I had studied experiment I'd be able to build all the things that my son wanted to build but, hey, he can build those things now.