Jerrycans are one of the first things to end in our surplus boxes.
They were used by the main contenders of WWII and virtually all modern wars and we never have enough of them, specially when you are into desert fighting.
So I made up an easy and cheap way to do as many as I want. This is the result:
Do like this: use a hard kind of styrofoam, the kind that comes in 3mm thick and about 60x120cm plates and that you can find in DIY. With a little luck your local supermarket can give you some of this material as some brands use it for advertisements.
Mark rectangles with the blunt part of your X-acto 7x4mm (approximately or the size you like) and then cut them.
Cut a small top fraction to mark the handler.
Use the blunt part of the X-Acto to make a hole for the handler. Press deep.
Do the same for the characteristic X on the main surface.
I also made an oblique cut at the petrol/water exit corner that you can see in the 1st picture.
And here you have. Plenty jerrycans at no cost at all, only some time of course.