Here is my adventure into another bed. We got a queen sized mattress from a family member and didn't have anywhere to put it yet. Eventually I wanted to build a murphy bed for our playroom but knew that wouldn't happen till next year (er, later this year) so I built this in the meantime. I had been wanting to build one for a while but knew Charles wouldn't like the style for our room, so this was the perfect solution. The entire project cost me about $70 to build. Right now m little toddler sleeps on this and it is so cute to see him only taking up the tiniest little bit of bed. Good news, he has only fallen off like twice seeing as it is so big!
HERE are the plans over at Ana White if you want different sizes or to see her plans.
Here are my plans if you want to build your own like mine (which has some modifications).