Summed up, Large Dehydrated Coco Fiber/Coir is going to be at most peoples local garden supply. Sold in bricks about the size of a boot box. Hydrated, it is a wheel barrow load. Can mix indoors in a large storage bin. I use it because the price is great. $15/per... Also, it holds moisture GREAT. Resists mold. Eliminates odors. Easy to scoop out solid matter. It otherwise stays clean, just gets topped off with fresh, and misted as needed. It works as well for green tree pythons as it does Short tail pythons. STP’s seem to love it. They mat down deep and dish out their hides good.
I also like using a large thin piece of slate stone for the ball pythons. At a shallow depth, directly on the bottom to get as much heat as possible. My thermostat probes are attached to it. Then place it on bottom and bury it shallow. They’ll sweep it off just like they like it. The probe sets on top which is often also in direct contact with snake.