Remember the Vortex Dome? It is an amazing desk toy that puts on a mesmerizing display when spun. This Handmade Rheoscopic Fluid Dome is a tad bit larger. It measures 32 x 4 cm and comes with ball bearing required for the spinning mechanism. You can spin this with hand or using a strong magnet.
This particular version weighs about 3kg. You can find smaller versions on Etsy.