We've sold over a dozen PSI Kit Kaleidascopes at our last 3 Craft Shows and only 4 or 5 of the Egg Type. They attract and hold a lot of people at out booth. They are easy to make.
What really went over good for us, were ones that I made out of limbs. I cut off sections of limb [cedar, walnut, cherry, even some grape vine], drilled, then turned them leaving some of the bark on for accent. These I had to finish with several coats of lacquer. May sound strange, but those of us in the Missouri Ozarks have well defined taste....LOL