They do make it easy but they are possibly not the cheapest option.
They usually come in a size of 6ft x 3ft and you can make them into pretty much any shape you want.
I've got two runs, one of them is 6ft x 6ft x 6ft high and the other is 6ft x 6ft x 3ft high.
The panels for the 6ft tall one I got from a man on ebay, they were £150 in total which is for 10 panels, including one door panel. If you try and order them individually they are usually £20 ish. If you PM me I can give you his name / phone / e-mail, he is based in the midlands but will deliver further if you pay for it.
My 3ft tall one I made myself. It's not that difficult if you can screw a few pieces of wood together but it does take quite a bit of time. Using an electric staple gun makes things a lot easier.