Reddit reviews Nordic Mellow Art Portfolio - 20 x 26 Inches - Swedish Soft-Sided Portfolio for Artwork with Shoulder Strap, Navy Blue

I made my own Bastard box that works for 4x5 and 5x7. Here's a list of materials:

• 32-gallon fold-a-tote: The actual box part
  
  
• Sacrificial film changing bag: For the armholes
  
  
• Rosco #19 Fire gel: For darkbox window(s)* Light safe indoors but outside you'll need to cover your head and box with a shroud of some sort to be safe. For the side windows I cut I used Rubylith sheets. You can't see through them so they only work on the sides but they are completely daylight safe.
  
  
• Tray stand: For setting the box on to work
  
  
• LED Headlamp: Has a darkroom safe red LED to illuminate inside
  
  
• Kitchen timer: for timing plate sensitivity. Fits handily into the transparent side pocket on the box.
  
  
• Portfolio: For toting the flattened darkbox around in.
  
  The box is made of thick cardboard so it's easy to cut through with a knife or razorblade. After cutting I taped the edges with black gaffer's tape to make it look cleaner and to prevent any particles from falling into the working area. I cut one big window in the top (for the Rosco gel) and one on each panel in the back (for the Rubylith).
  
  For the armholes I left the cuts rough so I could use a high strength glue to adhere the arms I cut off of the film changing bag. I glued them to the cardboard under the nylon fabric of the box. After that had dried I taped around the edges so it looked cleaner and provided a little better seal.
  
  For the illumination inside, I took the strap off the LED headlamp and stuck some velcro squares to the back of it and to the inside of the box. This holds the light perfectly and still allows the headlamp to tilt up and down for the perfect angle.
  
  The only other thing I do is tear up thick magazine pages and lay them down on the inside along with something like a puppy pad or some paper towels to catch any drips.
  
  Here is an imgur album with some sample images.