I believe there are plans you can buy off some furniture plan websites. Google them and see what you like. A king size bed is a big unit. Make sure you have the space to set it up and to make sure it all fits. The hardware can be bought from online places. I have done a few over the years. Just remember to add good support in the bottom cross pieces. They will be supporting your mattress, which will be wide. I make T shaped cross members and use lots of them. I make mine from maple.