Here's how I built our Murphy bed with a couch without expensive hardware and a simple, easy design.

I put together the plans in a (hopefully) easy-to-follow PDF with full material and cut lists. Check it out on Etsy: https://www.etsy.com/AKDIY/listing/14...

Here are the locking hinges I used for the support/shelf: https://amzn.to/3WfRM6Y
There are many Lazy Susan bearings available, but this is basically what I used: https://amzn.to/3H9opPm
This is the foam we purchased for the cushions: https://amzn.to/3ZHW2za
And this is our mattress: https://amzn.to/3HdvrTt
(paid links)