I ran across a program in my downloads and figured it deserved some notation. I’ve only put it to use once when looking into the Toomre-Q parameter (disk stability), but I can see where it may come in handy down the road. It’s basically a geometrical toy set called C.A.R.Metal. You can define angles/lines/circles/vectors/etc., then move those points and everything dynamically adjusts! Great for messing with angles and the like. Here’s an old image from my toying with it for reference: