Go study ergonomics. Go measure your biometrics. Go compute the load factors and necessary structural supports. Go design the contours and material attachments required to make something that is perfectly comfortable for you, rather than just cribbing someone else's work.
I have build my own bed. The only thing I have measured is the bedspring I was reusing from my old bed. For the rest, I have put together some plank in a way the my bed look like a japanese bed. (eg: no mine, but similar). What is its load factor? I really don't know, I just put some wood plank together. What where the structural support needed? I really don't know, I just put thing in a way that everything stuck together thank to gravity and need no nails or screws.
Then if it happens to look like a commercial design, you have a nice solid legal ground to stand on and say "I made this on my own".
My bed look like any commercial design of japanese bed for sure. If a company come after me saying I have stolen their design, I still can say "I made it on my own", but if I need to prove that I am fucked up because the only proof I have is my own saying and that will not stand before a court.