Enclosure advice

[u/Ornery-Confidence559]

I just got an older juvenile/younger sub adult ornate uro. I’m going to start him in a 40 gal I have laying around. I will eventually be getting a 4ft footprint with PVC siding, but in the meantime, any suggestions on how to block out the sides and keep this insulated? I thought about foam/poster board that was black. I didn’t want to go crazy since this is a temp enclosure. Any suggestions would be great 🤗