Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2501390. I enhanced the "Trammel of Archimedes" by Madox to a three-way-version to realize the same functionality (nothing) with a bit more effort. It's drawn from scratch too but I tried to keep his design. The slider is unmodified and uploaded here only for completeness purposes. The instructions are the same as provided by madox but you'll need one additional slider and screw.