
You can also buy animal heating pads ... they go under the metal pan and stay at a low constant temperature as not to over heat the chins.
If not that ... a wooden hut, or even a cardboard box, fairly well enclosed will also help them hold their body temperature in a confined area.
Some people will place fleece in cages, but beware ... lots of laundry to keep it clean.
Lots of hay, as long as it stays clean and fresh, is nice and warm for chinnies. Do keep in mind, once the hay is urinated on or gets wet from water, it can mold quickly. Keep a close eye on the hay and change it out about every other day.

Jo Ann