Here’s a new version that forces rugged gem to be installed system wide, although I don’t understand why.
https://raw.githubusercontent.com/samaaron/sonic-pi/e207c1ce6c2d006a4d5a4fb7adbc3a75695f5054/app/gui/qt/build-ubuntu-disco-app
@nlb you can change the script as much as you want, but it looks like you didn’t compile it succesfully yet? 