Turns out I didn't need to code one from scratch, here's an implementation for creating a convex hull: https://www.cs.ucl.ac.uk/staff/S.Pilgrim/maya/

You will need to compile the code with the Maya SDK however.

You could also use Qhull, https://www.qhull.org/ and use the application qconvex. It can output in an OFF format, which you can then convert to an OBJ, which can be imported back into Maya.