I been using google sketch
www.sketchup.com/try-sketchupI find its really good.
So for all the diy chicken hutches ;-) Its easier to put pen to paper (mouse to keyboard) and might save you costly mistakes and save you materials etc.
Here is ma latest Im gona make some automated gates !!!! good luck!
then im gona make a gazebo!!!
Its a good basic 3d modeling programe and it give you dimentions. 2 hours and you be an expert !