Hello
Here's a link to a thread from a while back - good if you can get curved steel
http://www.accidentalsmallholder.net/forum/index.php?topic=13045.msg127157#msg127157But it's reasonably straightforward to knock something up for a few weaners
A lady I collected pigs from had pallets for sides with feed bags and chicken wire on top as a roof. I 'adapted' it to suit Scottish weather (using a fibreglass roof panel off a VW camper and lined the pallets with hardboard and stuffed with straw)
Our first ever arc (still very much in-use) was an unused steel oil tank - we cut a doorway and a loading window (for topping up the straw) and it's great
Wood has better insulation values than metal, but wood is more easily chewed than metal
Recycled plastic sheets are cheaper than marine ply and Solway Recycling do a good range of pig houses made from it - not
too out of the way price wise - I've not used them for my pigs, but have closely examined them and reckon they'll be good. I'd say it's worth getting one with a floor or making a raised floor to fit inside - especially with the weather we've been getting of late
It saves on the bedding a bit as it stays drier
HTH
Karen