In our paper "Cooling a levitated milligram mirror to the ground state using Pound-Drever-Hall feedback locking" we describe how to engineer a levitated particle to the quantum ground state of motion by affixing a mirror to it, making another cavity with a fixed mirror, then PDH-locking the cavity formed. To do this, we developed code to simulate the entire PDH feedback loop and Brownian motion of the particle, to model the optical forces and modes within the cavity, and to model various noise sources within the feedback loop. All of that code is contained here, and can be used to fully reproduce every plot from the paper.