It was built by my husband out of re-cycled materials. The door is left open and it has become home for a myriad of wildlife. My garden has won an award locally for being wildlife friendly and the wild shed is part of this. The hedgehog summer-slept in a palstic compost bag under my potting bench, having dragged in leaves and grasses to line it. Mice live everywhere. In stacked plastic pots and in the roof. The roof felt is all ripped and is seen by bats as a perfect roost. I found bits of butterfly wing everywhere and found out that it was the bats feeding place! Ladybirds and butterflies pass the Winter in there. Then come the Spring, the wren and the robin have nested in there. Of course it is heaven for spiders of all kinds!
Made of re-cycled windows and roof tiles. Use natural roof felt as it is wildlife friendly. The main secret is not being tidy. Undisturbed corners and mindful neglect are key. No nasty chemicals stored in there or used in the garden.