Created a foldable light box out of

• cardboard
• painter's tape
• some white cloth
• double sided tape
• white paper
• four round 10x2 magnets
• four M5 nuts

Tools:

• Scissors
• knife
• hot glue gun
• pen

The first two picture show the general layout. The flaps you see in the first picture to the left are just painter's tape with magnets to hold the thing together when it's put together for use. You can also see - in the third rectangle from the left - the two nuts that the magnets hold on to.

Plugged together:

First light: