I built this shed out of 70% scrap timber (knocked down packing cases etc) and second hand double glazing out of skips. It is all double skinned and interwall insulated, fully electrified. So tightly sealed not even a spider can gain entrance. I use it as a workshop (also a comfortable office with a computer which I built from spare parts from car boots, works perfect, even got internet) so I can make other things like the shed next to it (built from scrap etc) and also the cold frames (out of old double glazing units) for propagating plants for family and friends. I also made the seated Arbour for my wife (the shed widow!) to sit in when I am hiding in the shed, complete with inbuilt optical illusion (all from scrap again) and the Gothic style bird table ( made again from offcuts) so my wife can watch the birds in winter eating my dinner which I never get time to eat. The Japanese style bird table I made for my friends wife, scrap wood again and the roof constructed from an old venetian blind to look like slates. I built the Dovecote from scraps and offcuts as per usual but I covered the roof of it with screening from a garden centre to simulate thatch. The local crows chased all my doves away but it's a nice feature on its own. The BBQ I constructed again from mostly thrown away scrap, the doors are from a kitchen, the T&G was once used to clad someones hall, the backplate used to be a single bed headboard and the whole thing is bolted onto the metal framework of an old pub domino table. The tiles were left overs from a kitchen. The actual BBQ unit on top was from B&Q and was nearly consigned to the tip until I gave it a new lease of life. We use the thing almost every time the weather permits.
The only snag with committing so much energy into such a project and making such a useful and comfortable shed is that you are very reluctant to ever want to move house again even if your other half wants to, pity I can't pick it up and take it with me.