So relaxing, maybe I'll just stretch out for a nap.
Mesmerizing Sine Wave Desktop Toy

Available as a 3D printable file from JBV Creative, this sine wave machine features marbles that roll in a sine wave as the machine is cranked. Hate cranking? Get creative and add a motor. Or a car engine! JBV also sells the file for a wave machine that’s only 8 or 16 horseshoes long, in the event your desk is actually a card table. Is this going to be the must-have desk toy for executives everywhere? It may be briefly, but nothing will ever top a Newton’s Cradle. Or, in my case, the plasma globe I bought at a Spencer’s in high school.