It's made with 3/4" PVC pipe. 2' tall X 4' wide (but divided into two sections, each 2' wide) X 6' long. Chicken wire held ontp the PVC frame with cable ties.
The roof is also made with PVC & chicken wire, plus some wooden fence boards. One board is the length of the tractor, the other two attach to form a large I. The ones at the ends are probably 4" wide. The one in the middle that goes the length of the tractor is probably 7 or 8" wide--basically as wide as I could find of fence pickets. They are screwed together into the I shape. I formed PVC into two 2'X6' lids and covered them with chicken wire, then hinged the panels to the center board with conduit holders.
I periodically think about attaching the top to the tractor, but it is easier to move them separately, and so I haven't. I have shade cloth cabled to the top to give summer shade. In the winter I covered with a heavy PVC(?) tarp that is 10x10--kept them dry & warm.
I have a similar tractor that is 4'x4'. Not sure which size I prefer--they both have their uses.