I've done so, way back in the days of the first ultralights and before Part 103. The aircraft was a Maxair Hummer; a V-tailed Xenoah G25 powered piece of irrigation pipe, which witnesses said looked like a witch on a broomstick in-flight. Got maybe 40 hours of time on it, too many military moves and a crash put paid to my confidence in it.
The fuselage still resides in my backyard. I could probably get it airworthy again, but with literally nowhere to go (the Washington DC restricted zone starts 5 miles west of here), it's not been on my plate of projects.
No, I won't sell any of it. I'd be liable for the next three lifetimes for any mistakes someone else dies from, regardless of if it was actually caused by something I put together.
Edit: Found a picture of the bird. Not my airframe, but same series.