Eddie Van Halen's musical genius is unquestioned -- turns out the guy was a bit of a design wiz too, and the nuts and bolts of his iconic inventions could soon be yours to own.
Memorabilia collector Eric Kuck tells TMZ ... he owns an original U.S. patent Eddie submitted in 1985. It includes a mockup Eddie submitted for his "musical instrument support" device, which is really just a guitar body rest that allowed him to free up both hands.
As for how much the patent docs could fetch, Kuck tells us the sky's the limit ... especially since Eddie passed away just last week after a long battle with cancer. FWIW, Kuck says he paid $800 for the paperwork about 15 years ago through an auction ... obviously, it'd be worth a lot more now.
One last thing ... Kuck says a portion of the proceeds will be donated to the American Cancer Society and the Free Rider Fellowship Church in Plant City, Florida.