[poliss]

They're called Nissen huts, spelling it nissan is a trifle unfortunate considering the era they are from.
A quick search on Google found some 1/72 versions from Amera Plastic Mouldings.
Website http://www.amera.co.uk/172nd.php?action=Ad...h%20Battlefield

 

[poliss]

I see Airfix, (now owned by Hornby), have a Nissen Hut on their newly opened website in the WWII USAAF Airfield Set. Could be a few useful things in the range.
http://www.airfix.com/airfix-products/dior...eld-set-a06903/