Netblock UFO, Patented by K. Chan 1997, purchased from Mefferts 2006. (plastic, 3.5 inches)

Sando Ring, Patented by Z. Pataki et. al. 1996. (plastic, 5.5 inches)

Each of the three balls can rotate, and so can the halves of the balls. Also, the upper and lower halves of the puzzle can rotate with respect to each other (so it is possible to mix up the eight quadrants of the three balls with each other). This is a relatively easy puzzle where you can solve one ball at a time. Jaap's Page prersents a solution.

Further reading:
Jaap's Page, from: http://www.jaapsch.net/puzzles/ufo.htm
Chan Patent, from: www.uspto.gov - patent no. 5,628,512
Pataki WO Patent, from: www.epo.org - patent no. WO96/08297