Started: July 2020 Completed: July 2020 Released: July 2020 I made a Reuleaux triangle with Lego. The Reuleaux triangle is obtained by drawing an arc around each vertex of an equilateral triangle. By using a 1×4 curved slope, I was able to create a fairly accurate Reuleaux triangle. I made the square frame with the Reuleaux triangle inside.  The Reuleaux triangle can be rotated while inscribed in the square, because it has a constant width.  I devised a gear that makes Reuleaux ‘s triangle revolve.   The luminescent round tile is attached to the top of the triangle. In a long-exposure photo, the trajectory is a square with rounded corners．   The mechanism in which the Reuleaux triangle rotates around its vertex. The yellow-green frame draws a square trajectory. Here’s a further development. The square frame with arms rotates while engaging the pins. The last mechanism is based on the following videos: Title: sankakukanketu (2014) Author: araieng URL: https://www.youtube.com/watch?v=rUP5bylFJgc Title: Reuleaux Triangle Intermittent Pins Mechanism 3D Model (2016) Author: trinityscsp URL: https://www.youtube.com/watch?v=8HUVuycpaiY