I have no idea where you could locate these, but even outside of the project I’d love to see two Disney TV specials commissioned to tie into the film’s release in 1979 - The Adventures of Major Effects and Black Holes: Monsters That Eat Time & Space. Both feature effects work by Mike Jittlov, and I’ve never been able to find copies of either despite my best efforts. (A 20-minute excerpt from Major Effects is on YouTube, including some of the Black Hole tie-in footage - https://www.youtube.com/watch?v=e6PBnuA-yWc)