The idea of making a latensification chamber for those with limited darkroom space got me to thinking.
Here's one idea...
Make a 2-part box consisting of a base unit to hold the film and a slip-on cover box with a "window" covered with plain 'ol black polyethylene film. In case you haven't noticed, the common 2 or 3 mil black plastic you buy at the local hardware store is not 100% light proof. It actually lets 1 or 2 % (???) light thru it.
With a bit of experimentation, one could figure out how many layers will be needed to reduce the light inside the chamber to the proper level for 15 to 20 minutes of latensification. (I'd guess that 2 layers will do it in an indoor situation). The "window" in the cover box should be the full length of the film to avoid uneven light.
In use, you'll need to find a place where the room light is uniform and repeatable. Bouncing a light off of the ceiling and making sure no bright light shines directly onto the plastic "window" is probably the easiest way.
The base could be a simple affair, made from 1/8" masonite or 1/4" plywood with a frame made from 1 x 4 boards. By making the frame with a 1/4" space between the boards, a light trap is created. The cover box could be made from black foam core with the black plastic taped over the "window".
The sketch shows the chamber used horizontally where large format films are merely laid on the floor, but roll films will argue as you try to clamp them down. It could also be wall mounted where roll films will behave, but large format films will take more care. Lighting for a wall mounted unit will take more thought.