crescent shape made by inverting an ellipsoid on a sphere

thingiverse

This is a nice crescent shape made by inverting an ellipsoid on a sphere. The pictures show the ellipsoid in yellow, and the crescent shape in green. The sphere used for inversion is the framework. I made a hole in the top so that if you glue the pieces together you will have a container, but it is really about the shape. If you want to rebuild this from the source (feel free to modify), here is the tool chain: 1. Run octave (https://www.gnu.org/software/octave/). The files "surfplane.m" and "savestl.m" are needed to generate the stl files. Execute the octave file blob33_2.m to make the two stl files "blob33_2_outer.stl" and "blob33_2_inner.stl". The first is the outer surface of the shell of the object. The second is the inner surface (negative space). You can print the stl files if you like, but they do not have all the features. 2. Run "blob33_2.scad". This takes the two stl files, combines them into a hollow shell that it splits into two. It then adds a lip. It makes a top and a bottom. Making the lips in a general way uses the Minkowski function, so it takes a really long time to complete.