Tonight I machined a nice little heatsink to replace the one that I drilled out too large. This one is a solid block of aluminum that I salvaged from some machine that was being junked. It should work well enough without fins, for my purposes at least. I also made a hole for a setscrew and tapped it. The whole thing turned out nicely and I like how it looks - clean and professional. The Aixiz housing goes in the hole and is held in place by the setscrew.
Lastly, I began to look at the code I will be modifying. I am using Python code from here. I need to change the code from controlling bare H-bridges (which take four inputs) to controlling the EasyDriver stepper boards (which take one step input and one direction input). It may be a challenge, but with the prize of a laser cutter at stake, I am sure I can do it!