Best substrates for changing temp

[Black_Inky_Eyes]

Okay thanks guys!

Yes I had already seen that terrecotta idea from ErinsAnimals and was planning to get a deep pot and a small dish so I can put ice packs underneath the dish in the pot which will be submerged by substrate.

If you're confused just search ErinsAnimals DIY cooling pad. It's a few years old so it's demonstrated with her previous hamster Potassium RIP.
EDIT: I've just noticed serendipity's mug idea and that seems much more cost efficient so I may go with that.

Thank you mangoandmimi for the advice, once I'm done with research and finally convince someone to help me build the detolf since I know it's a two person job.

[Pebbles82]

Definitely more cost efficient I would be a bit worried about putting an ice pack in the cage to be honest. Anything ceramic or terracotta of any shape is fine. When we had a heatwave one year I had two ceramic mugs I used and would swap them round - kept one in the fridge. When the one in the cage warmed up too much I'd swap it with the one in the fridge and put the other one in the fridge.

Teracotta is quite good as it's absorbent and you can just sprinkle a tiny bit of cold water on it to cool it down and it's soaked up.

We don't often get heatwaves in the Uk! Or for long - so it's not an ongoing thing

A fan in the room can help as well.

[Black_Inky_Eyes]

Thanks, serendipity!

Yes, I think I'll try that one mug in the fridge and one in the cage, although it's not quite warm enough now so I like to just provide a normal mug as a toy/hideout.