The 3/4" mdf was cut to leave an overhang and screwed to the 2x4's. Due to height constrictions the stage height was only about 4 1/4" which made it somewhat difficult to staple the carpet later on. If you can, make the stage higher so that you can get a staple gun underneath the lip...
The rear seating platform was constructed from 2x10's
Covered with the floor underlay. You can see the opening in the front for the dryer duct used to cool the projector hush box. It's routed under the platform and then through the wall to the left and under the stairs.
This shows how the
rear steps curve was created. I simply used two layers of the fibre board
and nailed it to the joists. The rope lighting was first hot glued to the
wood but it would soften up after the lights had been on for a while and
fall off. I ended up using small cable clamps and screwing them on.