Firstly I am rather new to concrete and casting so please forgive any glaringly obvious mistakes I make along the way, I know there are definitely some things I would do differently next time around (more on that later) but if you have ideas on how any of this could be improved please share in the comments. With that said, this is how I made my own concrete pinhole camera...
Step 1: Making the Cast - Part One
The body of the camera is basically a box shape with two walls inside that create separate compartments for the film to travel through. The first photo shows the dimensions of the inside part of the cast which I built out of laminated sheets of 5mm foam. I then created a box to enclose this inside part which when poured in concrete would create the walls of the camera. Finally I found a pen which had about the right diameter (12mm) to make the hole in the front - where the pinhole would be attached, and also the two holes in the top - used for advancing the film and rewinding the film once it is exposed. I glued these three pieces in place before pouring the concrete.
Step 2: Making the Cast - Part Two
The base fits snugly into the bottom of the camera to make it light tight. I made my cast being generous with the measurements then using a file I shaved the edges off the base until it fit snugly into place.
Step 3: Pouring the Concrete
Step 4: De-mold & Clean Up
Step 5: Detailing & Paint Insides
Step 6: Make the Pinhole
Other methods for making pinholes can be found here: http://silverbased.org/pinhole-101/ that link also describes different ways to measure the diameter of the pinhole you have created so you can work out the correct exposure times later on.
Once you have created your pinhole and attempted to measure it you can go ahead and glue it inside the body of the camera.
Step 7: Making the Shutter Cover & Film Winder
To make the shutter I simply found some thin plywood and cut it out using a hacksaw into a tear drop shape. Once I had smoothed out the edges with sandpaper I drilled a hole near the top and glued some black felt onto the back to make it extra light-tight. I then scratched out a hole where I wanted the shutter to be attached to the camera and used a screw covered in glue to fix it to the front of the camera (I then covered up the screw head with a dome to make it a little prettier). This is one of those things that if I had thought ahead maybe I could have set a bolt into the concrete as I was pouring it to make attaching the shutter a little easier later on.
To make the winder I used two pieces of wooden dowel one 9mm which I cut a slit across with a hacksaw so that it would grasp the two small teeth in the top of the film canister and then I used a second larger piece of wooden dowel and attached it to the top to make it easier to grasp and twist.
Now if you put it all together you should have a functional camera, however if you are likely to go traveling around with this camera there is one more thing I would recommend to do, use two bands of rubber (I cut mine from a bicycle inner tube) and slip one over each end of the camera to hold everything together, that way it is not likely to come apart in your bag or as you move around from place to place.
Step 8: Loading Film
Step 9: Making Photos
So to take photos I simply use my hand held light meter, plug in the ISO of my film and take a reading (if you don't have a light meter you can use your camera to do the same thing) then I can refer to the numbers below by Dr Evan Reece (another NZ photographer and pinhole maker, website here: http://www.ejreece.com/) to figure out an approximate exposure:
1.2 1.4 2 2.8 4 5.6 8 11 16 22 32 45 64 90(the approximate aperture of my camera)
Shutter Speed/Exposure Time
1/1000 1/500 1/250 1/125 1/60 1/30 1/15 1/8 1/4 1/2 1sec 2sec 4sec 8sec 16sec 32sec 1min 2min ...etc
Example: You meter F.11 @ 1/60 of a second
To get the exposure simply count the steps from the aperture you metered (in this case F.11) up to that of your camera (in my case F.90) so for this example there are 6 steps from F.11 to F.90, then you simply count that same number of steps on the exposure scale so in our example we start at 1/60 of a second and count up 6 steps so we know the exposure time should be about 1 second.
When you come to the end of your film simply switch the winder from one hole on top of the camera to the other and rewind the film right back to the beginning before taking the camera apart to remove the exposed reel.
Step 10: The Results
My nervous wait is over - the film has been developed and it has images - yay! Unfortunately the photo store had some difficulty in scanning the images as they turned out slightly bigger than standard 35mm format so I did my best to stitch them together and match up exposures etc... however there are some places which seem to have been missed in the scanning and some frames which are sharper than others but ... oh well.
So overall the look of the photos is very lo-fi - they are in very soft focus and there have been some light leaks, and a few frames which have grit/dust on them, but overall I kinda really like the pictures especially as I wasn't expecting perfection first time around and I was relieved to find any exposures at all! They also have super rough edges and the images extend right out to the film sprockets which you can't see in these photos - I wish I had a scanner of my own so I could do some better reproductions. Anyway I had so much fun making this camera that I think I will move on to concrete camera version 2 and see if I can't fine tune it and figure out how to get it working even better. If anyone else makes their own concrete camera I would love to hear about it/see your results!!