A helped a friend put one up, he bought it from a proper shed place. It was super simple but we did not do a concrete slab we used paving tiles. It was great, eventually we put sound proofing in there and he turned it into a mini recording studio. Bigger than the small bedroom lol. It was far from soundproof but it didn't annoy the neighbours.
I remember there was a leak in the roof after building it but we just waited to see where water came in then went crazy with mastik. After a while all the holes were plugged and it was water tight.
For garden use is solid, if expect it to last a decade or more. But the sheet metal was only a couple of mm so if you throw a sharp tool into the side or will dent and possibly rip. The walls were not designed to hang heavy equipment but the roof crossbar seemed solid.
I'd given up on lemmy because every so I had tried was unfinished and unpolished. I tried sync and finally felt like the user experience wasn't getting in the way of content.
I'd love to support foss, if a genuinely comparable experience existed.
I'm glad to say that sync has revived my interest in lemmy.