$10 DIY Film Changing Box Plans: Battle of the Film Sweats

In a departure from normal pencil-related programming, I want to share a project I've been working on to develop analog photography film at home.  For the uninitiated, it's pretty easy to develop film at home.  You just transfer your exposed film to a light-tight tank, add some chemistry, and you end up with film negatives to scan. This post focuses on the part where you transfer the film into the light-tight tank.

It takes complete darkness when you transfer your film from the cartridge to the developing tank.  There are 3 main methods for this:
  • A darkroom
    • Expensive! You need an entire room that you can light proof...that's a big commitment
  • Film changing bag
    • A light-proof bag that you stick your arms into 
    • ~$25 on amazon
  • Film changing tent
    • ~$85 on amazon
Film changing bags are cheap and that's what I've been using up until now.  These bags are normally made out of cloth that is light-proof and doesn't breath.  You can't see what's going on inside the bag, and you are trying to do tricky things with the film by feel.   The bag's cloth never fails to collapse around your hands, stifling them.  You're hands are already sweating like a pig in church, which makes it harder to work with the film, which make you get stressed out and sweat more...in a never ending cycle of misery.  This phenomena is the dreaded 'film sweats' and has been the bane of my film developing existence!

The normal solution is to shell out $85 and get a film changing tent to give your fingers more breathing room.  But hey, the whole reason I develop my own film is to save money and I wanted to find a cheaper solution.

My film changing box gives you the advantages of the film changing tent but it's a lot cheaper.  It doesn't fold up like a tent, but it is a box that you can use to store all of your film developing supplies in when you're not using it.  If you'd like to make your own, follow the instructions here.


  • Sturdy cardboard box 
    • My box was 12 X 18 by 14 tall.  I wouldn't go too much smaller
  • Extra cardboard or foam-board
  • Black duck tape -- $8
    • Don't cheap out here, get the BIG roll
  • Thrift store dark colored hoodie -- $2


  • Knife and/or scissors
  • Stapler
  • Straight-edge


Light Tight Box

Choose a box that is the right size for what you're developing.  Any light-proof container will work, and I think a black Rubbermaid type container might work nicely.  I used a heavy duty cardboard box that has double corrugation.

The cardboard itself is nice and light-proof, but you'll need to use tape to light seal up the box.

  • An iphone flashlight will shine through 1 layer of the black duck tape I used, so I used 2 layers everywhere
    • Each tape is different.  Use a light to test how many layers you'll need.  
    • Blue masking tape takes at least 8 layers, so it's not a good option
    • I haven't tested normal silver duck tape, but it's probably fine
  • Use multiple layers of tape to seal up any seams or gaps in the box.  Focus on corners especially

  • I folded the flaps inside and used black foam-board to line the bottom of the box for extra protection and a flat bottom.  Cardboard would work just as well.

  • I made a custom lid for my box.  I think it would work just fine to close up the normal box flaps and seal with tape, but I wanted something I could open and close easier.  There's lots of methods to do this, but here are pictures of how I made my lid.

Congratulations, you have have a light proof box!

Arm Holes

You need to be able to stick your arms into your brand new light-proof box.  This is where the old hoodie comes into play, but don't worry, the only sewing machine you need is a stapler.
  • Cut off the arms of the hoodie

  • Next, cut out 2 cardboard rings with an inner diameter big enough to stick your arm through and an outer diameter about 4 inches bigger

  • One layer of hoodie material lets an iphone flashlight shine through, so we need to double up the arms.  Feed the arm through itself so just a few inches of the sleeve end are exposed.

  • Use a staple to connect the doubled arm to the cardboard rings.  Pull the sleeve through the right, and work your way around the ring with staples.  Leave some cardboard exposed along the outside of the ring because we'll be taping there later.

  • Cut holes in the box for the arm pieces to go inside.  Place them towards the bottom of the box, and space them so it will be comfortable for your arms.  These should be about the same size as the inner diameter of the cardboard rings.  Then, place the sleeves inside the holes (sleeve end first)

  • Next, tape on the cardboard rings.  This tape is structural and also a light barrier, so use plenty.  After the outer cardboard is covered and attached to the box, add a second 'ring' of tape closer in to the center to cover up the staples.

Awesome, you have your light-proof arms put together!


  • I used some of the leftover hoodie material to make a skirt around the lid.  It may or may not be necessary, but it's easy to do and can't hurt.  I staples the cloth on first, then used tape to cover the staples and help hold the cloth on

Testing it all out

  • The most direct way to test it is to develop a roll of film through it.  If you've done your work well, you should have no problems.  That being said, make sure it's a roll of film you are willing to sacrifice
  • You can also try taking a long exposure with a digital camera inside of the box (make sure your arms are inside or you will have big light leaks through empty sleeves).  I'm not sure how effective or necessary this is though.

Be Creative

You probably have all of the ingredients you need to make a box, but be willing to experiment.  The first prototype I made is ugly as hell but works great.  It's just cardboard and duck tape, so if you make a mistake it's not the end of the world.  

  • My first prototype

  • Future Upgrades
    • I'm adding a light-proof fan and ventilation system to really give the film sweats what-for!

No comments

Back to Top