would be interested to find out what American and Canadian's prefered style of chook tractors are mostly used. mine is light-weight dome style, easy to move, easy to adapt

Bird

I have always had smallish homemade ones mostly just for chicks, not adults. i tend to use whatever I have laying around to make them when I need them.  I have seen several nice designs that were basically triangular shape that I like. if I ever build a permanent one for adults for some reason I think that is what I will go with. probably wood, because that is easy to work with.

what is yours made with? by dome do you mean....igloo shaped or an arched roof? I am always looking for new ideas..

Circular done, made from electrical conduit. tarp cover peged to ground so as not to turn dome into a kite, lightweight easy to move and also easy to lift enough to let them out, for good behaviour on occasions

Bird

My answer to that is so huge I wrote a big chicken article.