My double bed slides out by means of two skillfully integrated pieces of white oak commonly known as "rails". While I possess the tools to make new pieces should the old ones wear out, I was pleasantly surpised to see Steve offering brand new slides
Steve's offering is not a "kit", but it is the primary component needed for your project.
I have some
pictures of how my double bed goes together. There's enough information in the pix for a woodworker to build your project. Email me if you want copies.
The pictures are not detailed enough for the novice to build the finish project.