Looks cute with the little colored pieces.
Just a suggestion on how to do the windows.
I got some linoleum underlayment. (it is thin plywood like 1/8 inch thick)
Cut it to size and sandwiched it between the area to be windowed and some 1x3 pieces leaving one end undone.
This made a "track" for the plexiglass and it moves smoothly.
So figuring dimensions went like this:
12x12 window opening=cut the underlayment AKA lamboard to 26 inches x 2 inches
cut the 1x3 to26 inches
sandwich the underlayment between the 1x3 and the wall on the bottom edge of the window. Recess the underlayment so that the bottom of the underlayment is flush with the bottom edge of the 1x3 and both pieces are 3 inches beyond one side of the window opening screw to the wall. (Predrilling helps prevent splits.)
Do the same for the top.
Measure the distance from top to bottom on the end with the 3 inch placement and cut pieces for that. Use the same 1 inch recess.
Slide a 13.5 x 13.5 piece of plexi in and wala a side sliding window.
Or cut all pieces so that the plexi can just be removed when desired instead of staying in the "track".
I had to do sliders for mine since the sides are not easily reached. DH would not budge on doing another run so the second coop was built
in the run.