Construction of my sleeping box in Cedar Rapids is a topic I have had to think about for awhile. While I had many options, my chief concerns dictated much of the design. The biggest was transportation, construction, and the three month time frame. While I did have a truck to move to Cedar Rapids, my apartment would be on the second floor.
I had considered pre-building the box door. But my last doors were extremely heavy, and I wasn't fond of the idea of carrying all the box construction materials up two flights of stairs. There were various options for lighter weight boxes, but it seems a lot of effort for such a short usage duration. I didn't want to have to build anything on site that required cutting wood. All the cutting would have to be done outside, and carried upstairs. I decided to go an other route that took care of several of these problems.
The new box construction has been done using foil-backed foam insulation. I've used this material before to black out windows, and it works well. The price per 4x8 foot sheet is about the same as a 4x8 foot sheet of wood—so no real cost savings. However, it can be cut with a razor and it's messy like sawdust. It is also very light, although it lacks strength. The lack in strength isn't an issue—I do not need the box to hold any weight on top. Rather then using caulk to mask light on the sceams, I planed on using duck tape and aluminum foil. I ended up finding a metal tape that worked out better then the two step solution.
The door would be a major source of light leakage. Although a sliding door solves many of these problems, my box would no longer be made of wood, and the sliding door would be much harder to create. Instead, I used a top hinged door as I have in the past. For light, I added cardboard on the inside and outside of the door to try and create overlap. Since the door will not seal well by itself, I tried two magnets on the door with washers on the door frame. This works alright. For additional light masking, I added a towel to mask off any remaining light.
Ventilation again incorporates a blower fan at the back of the box. In my last couple of designs, I've found it's better to have the fan blowing air into the box, with the fan outside the box. For the exhaust port, I put a hole in the top of the box near the front, using the roof vent to block light. I need some more light masking on the exhaust light masking, but it it working, and there is fairly good airflow.
It has taken longer to setup than I had hoped, but it functions.