This is a set of basic corners and fittings so that you can use 16mm pvc electrical pipes in your garden. The original idea is from this
site where you also can order them if you live in Sweden.
The images show some of the many ways that you can use this in your garden, add a fine net around it and you have a perfect way to protect your bushes and trees from birds and other animals. They can also be used to make a small greenhouse or hoop house.
[UPDATE]
Also added 20mm versions since I got a request for that!