House for inside playhouse

Hi just wondering what people have inside their playhouses/ sheds for buns to snuggle up in. We have only recently moved ours into a playhouse which we haven't had a chance to insulate and as its been warm they have just had their trays to sleep in. Its suddenky got cold here and i need to sort out a warm sleeping area for them ASAP. Ive put a cardboard box in for them in the meantime but now i suppose i will need to get a hutch or something to put in there. I'm just reluctant because they are so expensive and it seems unecessary to have to have the whole hutch when all they need is the sleeping quarters.

On another note I've just been looking at hutches on the zooplus website and i cant believe the pictures on there of rabbits in teeny tiny hutches. I think i might have to email them and complain

I have their old double hutch in the wendy house. I have taken the front and sides off so the bottom tier is open with just legs holding it up but so they have another level. Iyswim