Aw! That’s an instrument I’ve not thought of for some time! I did a whole presentation on this creature at Uni, and made a javascript version that might still work, at least on desktop! :)
https://synthmuseum.thefunnybrain.com/
ooh also this page is worth a look :)
Aw, but I love my Yammy! 15 years on and it’s the only guitar I know will just take whatever dumb tuning I want to try, and it sounds okay doing it! :) poor little guy gets played as much as my nice ones!