I have a bed with metal bar slats similar to this: amazon.co.uk/d/B…USI
. I am happy with the mattress I have, it is a memory foam of medium thickness which is perfectly comfortable on a hard floor as well as wooden slats as was before on an Ikea bed. When placed on these metal slats however the mattress doesn't provide enough support and the slats are very painful, not mild pain after hours, it is unbearable to even sit for a few minutes. I have tried adding a second mattress underneath it but it is still not enough and bars can be felt. If purely adding a mattress, it would need to be a very high/firm one, probably coil spring type which I do not want.
What can I put on top of the slats to make them more of a flat surface? Something cheap, firm and durable, ideally not too heavy.