The jerrycan was actually invented by the Italians in Africa and adopted by the German Army sometime around 1937. The Germans called it the Wehrmachtskanister.

At the beginning of the Second World War, the British Army were equipped with simple rectangular fuel containers. A 2 Imperial gallon (9 litre) container made of pressed steel and a 4 gallon (18 litre) container made from tin plate. Whilst the 2 gallon containers were relatively strong, they were expensive to produce. The 4 gallon containers, which were mainly manufactured in the third world, were cheap and plentiful but they were not very robust. Consequently they were colloquially known as flimsies.

Whilst adequate for transportation by road in Europe, the flimsies proved to be extremely unsatisfactory during the North African Campaign and severely hampered the operation of the British 8th Army. The transportation of fuel over rough terrain often resulted in much of the fuel being lost as the containers easily punctured. The resultant leakages also made the transportation vehicles liable to fuel fires.

When the British Army saw the German and Italian fuel cans first-hand they immediately saw the advantages of the superior design. The containers had three handles on them to allow for easy handling by one or two people; the sides of the can were marked with cross-like indentations that allowed the contents of the can to expand; when filled, the cans retained an air pocket so that they would float on water and rather than a screw cap, the containers used a cam lever release mechanism. The British used cans captured from the 'jerrys' (Germans) -- hence 'jerrycans' -- in preference to their own containers as much as possible and soon began to produce their own cans that were exact copies of the original.

I've heard some people say that they were made of some type of plastic but this sounds pretty far fetched! I'm almost positive that they were made of metal exclusively but why don't more modelers show "banged up" cans that would be accurate with metal cans?

What were German jerry cans made of exactly?

I've heard some people say that they were made of some type of plastic

why don't more modelers show "banged up" cans that would be accurate with metal cans?