Build it.
How solid do you want it?
I would go for brick walls if it were a permanent fixture, at least one wall.
Full insulation, full electrics, water, etc. up to spec if it is permanent but you don't need to do all that initially.
If you just want a quick cheap shed, the only thing I would say is shiplap is your friend, and they now make smoked polycarb corrugated sheets in the asbestos profile, so single pitch roofing can be simple and tough. Shove some tar paper on the inside and insulate it, shove some ply up for some of the area at least to give you somewhere to hang things, and the one thing people seem to neglect is the floor, I like a wooden floor for my work area, if no vehicles are going in and out, and it is better to make it raised properly on joists and proper t&g with insulation underneath, not those chipboard panels, eughhhhh.
Is the area you have surrounded by walls or fence or what?
Oh yeah, watch those TV shows about sheds for inspiration!
I love sheds!
Currently working on a design for a fold out shed.
