As always, safety first. Using needles, pocket knifes, and fur sure the sharp edges of the can, ... be carefully!
Your first step is buying a can. I used a 50cl can as these ones are easier as they are bigger than the classic ones. With or without beer, empty the can and dry fully the inner side.
Open the lit using a sharp pocket knife. A canopener in my case did not work because the shape of the top of the can. Do not cut the entire lit; at the end it is easier to close the lit again when it is not completely removed.
Using a black spray, the innerside was made complety black.
Make a small opening using a needle, approx 3 cm from the bottom. Make a blanc out of regular paper and try to bring it into the can. Keep space open in the surrounding of the opening made with the needle. Remove the blanc paper again.
Now make sure you continue the work in a real dark room. Use only red light (eg. from a bycicle light) in this room. Take light sensitive paper a cut using the size of the blanc. I used sensitive paper Ilfor Multigrade IV.
Bring the this paper into the can and watch again not to block the opening from the needle. To keep the paper on its place I used double sided phototape.
Still in the dark room, close the opening from the needle with dark tape. Next step is to close the lit and seal the entire can. Use some tape as the can needs to out for 6 months in many kinds of weather conditions.
The can is now ready to be installed.
