I built a shed in the back garden, using mostly freecycled materials. Bought: sand and cement, screws, felt for under the tiles. Freecycled: bricks (hence the rather random assortment), roof tiles, timber and plywood (ditto), windows, door, and UPVC and aluminium frames.
I had made the trusses already – it took fifty minutes to lift the middle six into place and fix them.
Those composite beams are heavy – as much as I could manage to lift into place on my own.
The trusses weren’t so bad.
The shed is all finished and in use now.