materials for running water basin:
the plastic thing to attack the hose to your shower
a heat gun or a drill
a mask for fumes
a pen and a measuring tape
a saw to cut metal sticks in two pieces
the biggest plastic box (snalis) from ikea
4 to 8 alluminium sticks to hang drapes from ikea
(I used 4 pieces cut into half to develop 2 photos, you can use 8 to develop 4 photos)
Step 1: Prepare Material, Measure the Box
Cut your hose to desired length. It should be long enough to connect the base of your basin to the water source of your shower, and a little bit longer.
Measure your plastic box.
On the small side draw a vertical line in the middle.
Measure your photographic paper, draw a horizontal line shorter than the height of your paper, through all the sides. Draw another horizontal line just under the first one, the sticks will fit in between these two lines.
Draw another couple of horizontal lines near the base of the box. Here we'll put the sticks to hold the base of your photos.
On both small sides, draw 4 vertical lines on the left, 4 vertical lines on the right side of your first vertical line in the middle. The distance of the lines should be the same on both sides.
The distance between each couple of lines should be enough to put the paper between, but not too big that they fall from the sides.
(2 lines to fit the stick in, 1 cm space, another 2 lines to fit the stick in)
If you want to wash four photos at the same time, you should draw 8 vertical lines on each side.
Step 2: Put Holes in the Box, Put Sticks Through the Holes
2 on the right up
2 on the right down
2 on the left up
2 on the left down
same repeats for the other small side.
Take your heat gun or a drill, put a mask on your face and make 16 small holes.
Put 8 sticks through the holes.
Step 3: Put Other Holes, Put the Hose In
On the small side, where we did draw a vertical line in the middle, make a hole near the base of the box. This hole will be for the plastic hose, so it should be just a little bit bigger. Check the diameter of your hose. Put the hose in this hole.
On the other tip of the hose, put the plastic thing to attack it to the shower.
And it's done.
When you develop you photos, put the basin in your shower, fill the basin, insert the photos between the sticks and wash the chemicals. Excess water will drip into your shower.
Warning: I don't know what happens to the chemicals in the sewers of the city, I don't know how much damage can do these chemicals to the ecosystem.