Phase 1: I bought this sliding hidden door with wood I have laying around. I did have to buy some drawer sliders, but they only cost about $25 per set. I attached the sliders to the wall, making sure they are screwed into the door frame. I cut a hole in the hole only big enough for my fat butt to slide through at first. From the inside, the door frame was built. Once the frame is built, the drywall was cut along the frame. The fake wall is made of 2x4's that I ripped, so each strip of wood is 1.5" and 0.5" thick. These strips are attached to a 1/4 sheet of wood (maybe thinner, but I do not remember). On the wall above the hidden door, I used a 0.5" sheet of plywood and then installed more strips of wood. The key is to make sure the thickness of everything involved is the same, when finished.

I ended up burning the wood with a torch. I did not stain it or anything. I did mark it up to with some tools prior to burning it.

Here is a link for the drawer sliders.
Knape & Vogt 8400P 28 Side Mount Full Extension Drawer Slide, 28Inch, Pair https://www.amazon.com/dp/B0009VLFE0/...

Phase 2: I will install a latch/lock along with a security door on the inside of the room.