Not certain how permanent you need but I picked up a S/H double garage / steel framed tent type for shot blasting, about 6m square.
I think Machine mart do them.
I think they are good UV wise and strong enough to withstand most things.
Mine has an apron around the bottom that can be buried for extra hold down.
I think they are used a fair bit for car restoration, then took down when complete - like never!
New about £400ish
If I see a link will post.
Trago have them in several sizes. They look sturdy and very reasonable too so I've been meaning to get one to tuck away in a corner of the garden to hide all the junk machinery I seem to have collected. No security for anything valuable though.
Cheers,
John
-- Edited by John Leah on Tuesday 30th of September 2014 09:53:06 AM