The main structure of this playset is made from foamboard (available at Wal-Mart). I made the total playset 12" x 36", because I display all my customs on 1" x 12" shelving. The playset is actually in two parts: (1) the left alcoves & main floor and (2) the right alcoves. I made the right alcoves detachable so I could take pictures of the band and people standing around the bar.
I first measured out the dimensions of the floor and cut out the square. I then began making the alcoves. Each section contains two alcoves. I cut out 2 walls containing the arches and glued poster board inside the arches to form the ceiling of each alcove. I then cut and glued the outside wall to both sets of alcoves, and cut a small window in the outside wall. Before glueing the left alcoves to the cantina floor, I smeared spackling all over to give it an adobe look. Once it dried, I glued the alcove to the cantina floor. I did the same to the detachable alcoves and then glued the floor to the alcove. In the back alcove (on the detachable set) I cut boxes out in the floor and glued 5 action figure stands in the holes (I got a little messy with the hot glue).
Next I made the back wall, which is simply a piece of foamboard with two archways cut out of it. Once it was glued to the floor and stationary alcoves, I smeared spackling onto it to simulate stucco. Once all the spackling dried, I took both a blue and red marker and drew sorta trim lines aroung the cantina following the tops of the arches. Then I spray painted the entire cantina with beige paint, making sure not to completely paint over the blue and red trim lines. Once the paint dried the blue and red trim lines simply look like they have faded over time. Look close at the cantina scene in the film and you will see these trim lines.
I then took two pieces of background from Hasbro's cardboard cantina playset and glued them to the arch openings of the back wall. I also cut out the actual cantina and glued it to the floor. I also cut out the benches where Han and Greedo sit and glued them in the first alcove on the stationary side. The tables were made from film canisters.