We have the same problem with Alfie, we've bought him some lovely v. expensive beds and they've all been destroyed. We're using the same thing as you now, he has a plastic bed with old sheets in, it doesn't look anywhere near as nice or comfy as the old ones.

I think until they're older and they hopefully stop chewing then its the best bet. We put an old dressing gown in there last weekend but he just destroyed it.

He has got a 'special' bed in our lounge, a really nice wicker one, so far touch wood he's not eaten it, but to be honest he spends all his time curled up on our lap. We've also got quite an expensive eskimo bed, but the minute we put it down he goes into destroy mode, he just doesn't see it as a bed, just something to rip apart.

Let me know if you manage to find anything beagle proof!