This is something I wanted to build for a couple months, but I don't have a heated garage so it had to wait for spring 2015. Worth the wait.
Get a tailgate. After a little searching I found this gate off an early 70s dodge ram for $70.
Get wood. I picked up 10 pine 2x4s, 10' lengths. I had plenty of extra wood.
Build the frame for the seat.
Cut the rest of your wood to length.
Sand. Stain. Sand. Stain. Sand. Stain.
Step 6: Assembly
I built the seat frame. And put on the legs. Next was the tailgate then the seat slats.
Step 7: Arms & Final Product
Came up with an arm design on the fly with leftover materials from a previous project.
I let it sit outside over night. Applied a couple more coats of stain the following day. And that's it, took 3 days to make start to finish, working on it a couple hours after work each night.