I think the only legitimate DIY option is solar panels, batteries and an inverter. I'd probably use an RCD protected extension and unplug when not in use.
I'm wondering about making my own shed. But I'll probably just buy something and it's not going to have power 'cause I'm fortunate enough to live in a large enough house that I can escape my family without going down the bottom of the garden.
And make your own garage doors?