I have some ideas, but figured I'd ask if anyone knows of examples/writeups so that I don't completely wing this.

I have a fairly large closet in the center of the house connected to my main snake room, I was planning on sealing it up/building an area inside of it lined with foam insulation, and then installing heat tape, fans, thermostat. Not sure the best way of making a door into it yet, or if this is even an efficient design.