"Sandmation, Acrobat" is a "sand animated" acrobat. As is "Sandmation, Teeter Totter", this is a 3D printed version of an animated toy available for children almost a hundred years ago. Video of prototype is here: https://www.youtube.com/watch?v=PFbVLWH_Ph4&feature=youtu.be. Designed using Sketchup Make 2015, and printed in PLA on a Makerbot Replicator 2 using Makerware 2.3.3.42 "Standard" Settings (.2mm layer height, 2 shells, 10% infill). UPDATE: Added "Hopper, 8mm by 8mm.stl". This rotates the acrobat much faster.Parts I purchased: 1) Very fine colored sand (hobby, craft store, Amazon). Study "Assembly.skp". Print and assemble all pieces as shown in "Assembly.skp". After printing, remove the hold down tabs. Note there are two hoppers: "Hopper.stl", and "Hopper, 8mm by 8mm.stl". In the original video, I used "Hopper.stl", but if you wish your acrobat to spin faster, use "Hopper, 8mm by 8mm.stl". Test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required. Assemble as shown in "Assembly.skp". Comment if you have questions.