Out of all the hangers on around The Beatles, Magic Alex is probably the most fascinating. I don't think any other person in the world has had to put out a formal statement denying that he ever promised to build a flying saucer for The Beatles.
Idk about the flying saucer but in the documentary Get Back, there is footage of one of the inventions he promised to Lennon, a prototype hybrid bass/guitar with a rotating neck. It looks really bad, it'd probably be uncomfortable to play as no matter what you'd have strings chafing against your hand and I still don't know why the neck needs to rotate.
He was tasked to build the studio at Abbey Road and pretty much completely botched it for pretty much the same reason why hiring some random guy hanging around your local hackerspace telling tall tales to design a professional recording studio would be a disaster. But Lennon liked him basically because Alex gave him a box of blinkenlights to look at while he was high and John thought he was a genius.