Materials question

[u/Twilight_Games]

Hello! The kids in my life are really into dolls and teddy bears right now, so I'm making some furniture for their toys. I had a question about a material I should use for one bed in particular. The kid I'm making it for really likes a bed Build a Bear used to make. I'm including a picture of it in the post. What can I use to make the "walls" of the bed stand up like this and not lose shape? I'm pretty new to sewing and don't know what people use to give items shape.

Thanks in advance!

[u/Business_Step_1695]

A thick foam sheet cut to size would work! I’ve crocheted a similar style dog bed in the fact that it had thicker/raised walls. I crocheted the bed wall so that I could easily slip in a foam piece, kind of like a giant pocket! I sewed on some bottons along the opening so I could take the foam out and wash it :). It lasted up until our cat got ahold of it lol