This is actually my own bed in my room, it was really cheap at Ikea! Since I like simplicity in furniture, I thought I'd make it for my dollhouse. It's easy and quickly done.
This is the mattress support, it's out of foam cardboard because nobody will see it once your bed is made up. This is 9 cm x 10 cm.
Then I surrounded the support by balsa panels, so as to make the bed frame. I glued little wooden beads under it to make the beds 'legs', which aren't the same as the legs of the Ikea bed, obviously, but I thought little round legs didn't look bad on a dollhouse bed. I think if I had made them out of balsa, they would even have splintered and broken.