An impromptu photoshoot came about but I didnt have my lighting equipment. All I had was a speedlite but I wanted soft light (no harsh shadows) so I had to improvise. I had everything at my house except for the diffusion material, which was only $2 at a local fabric store.
Take your box and remove the flaps from the open end. If you're using a box cutter, be careful! Save the two largest flaps for the next step. (The open end of the box will now be referred to as the front)
Take the two flaps and position them in the box so they create a 45° angle from the bottom front to the top rear. Use duct tape to keep them in place.
Now take your box outside so that you don't get spray adhesive everywhere (it can be quite messy). With your aluminum foil at the ready, spray the interior of the box with adhesive (I used 3M Super 77 but for this, any kind will work), then line it with foil.
Now cut a small rectangle out of the top of the box that's just large enough to fit the head of your speedlite.
Cut out a square of diffusion material that's large enough to cover the front of the box and wrap around the sides a few inches. I used thin white nylon from JoAnn Fabrics. Put it over the box front (open end) and tape the sides down. You're done!
Now just tilt the head of your speedlite down into the "L" shape, then stick the head into the hole on the top of your new softbox. Set the speedlite to its widest coverage and adjust the power till your subject is perfectly lit!
*You'll need a sync cable or wireless trigger to fire your flash*