Semi-self-playing instruments are musical instruments which, once activated, will keep going of their own accord, serving as accompaniment while the player moves on to other instruments. This video features several such.
For more on these and other instruments by Bart Hopkin, visit the Instrumentarium at BartHopkin.com.
And by the way! Bart has recently released an album of his music, made primarily on instruments he's made. It's called Audiorium, and it's available through the usual download and streaming services.
