This is an eight part spinning mechanism which is apparently called a Trammel (i don't know if it actually is called that). This device is meant to draw ovals, but it is also just a lot of fun to play with. Unlike other designs, this used three sliders instead of two. It has a very smooth feel when spinning and is easy to print (takes 2 hours on 50% scale, 200 micron layers). Designed by me in Cubify Design, with the inspiration from a gif a friend showed me. Feel free to comment any improvements to be added.
I printed mine with 200 micron resolution, no supports or rafting, and then the other standard options on MakerBot software. I scaled mine 50% and it still works brilliantly. Scaling to any reasonable size and changing the resolution should work with no problems. Orient each part facing up to print, apart from pin. For the Pin, make sure to have the large part of pin on build surface. If using PLA it should not warp, but if it does, just use a little glue. You will need to print three pins, three sliders, one handle, and one main. You only need to print one handle so you have the choice of printing the regular one or the one with the finger hole. Very easy to assemble, if confused, just look at pictures.