I found it on ebay. Been hunting for a good one for over a year now.
Here’s some information on it from the Museum of YoYo History:
“The Duncan Tin Rainbo is a very unique model. Nothing similar has been made since. The patent information on the logo says it began production in 1934, but the length of production is unknown. The Rainbo consists of a tin body, tin inner and outer shells, with a metal axle. And inside the windows on the side, a tin wheel with multicolored patterns and designs. Throw the yo-yo, which actually gives good sleep times, and return it to your hand. Catch the yo-yo, and the color wheel continues to spin inside each side of the yo-yo. Because of age, rust is common on these. Not to mention most are well worn, because most have been played with for several generations.”
These rarely pop up and when they do, they are almost always pretty beaten up with a lot of rust. Often times the wheels don’t spin. Even then they seem to go for quite a pretty penny.
Apparently this one was forgotten in someone’s grandfather’s closet for decades…