Memory Foam Mattress
It’s worked really well for us, since then the dog spends about 90% of the time lying on it.
What you can’t see in the picture: the memory foam is in pieces inside the product, not in one solid block. For us, this was actually a plus, because it means the whole thing constantly shapes itself to the dog’s body.
It’s a bit tricky to clean with a hoover, as the hairs tend to stick in and get caught.