I have built and am using the wheel lift mentioned by EdenCamp. The axle is making the hole in the pine board oval. I need to figure out something else or improve the design.http://avianaquamiser.com/posts/Revised_chicken_tractor_wheel_lift/
Wheels are expensive so I want to be able to swap wheeled undercarriage easily from unit to unit.
I don't want to have to be grubbing around crawling on my knees to fit wheel shaft through coop.
Think this can be set under and locked in easily to get-n-go.
I also am setting here looking at babies in coated 1/2 X 1 mesh poultry cages and thinking if they were 4 times the size they could handle a trio or quad and still be moved around easily by hand. Tarp for shade or pulled completely over and even set up on bricks so the birds wouldn't get all wet and muddy when rainy. Pvc frame with an access panel, hanging food and waterer. All the benefits of free range, inexpensive unit, sanitary. Don't need a huge pen for small breeding units - need many small ones, easy to keep sanitary and clean.