Attaching the pallets - I had some corners of wood (from the stair company). I cut them at angles correct for the octagon shape. I then screwed one into the top and bottom of each pallet. This seemed secure. I then found some metal plates that are the correct angle, so I added these to the middle. I can crawl my 200 lbs. of flab in and out of structure without a wobble to the wall. The walls are secure!
Then, the center post is sunk in concrete with the ends resting in the Vs of the pallets. I only have a single screw holding each of the ends into the pallets, yet the concrete and center pole make this very secure as well.
I ordered a tarp through the mail that is silver and ideal for 'roofing outdoor structures', however, now, I can find no sign that the order was ever placed. The tarp would be a joke to predators unless I could rig a solar-powered electric wire or something. I do like to be able to clean and collect eggs (someday) without having to crawl through the little door. I have a fear that one day, I will crawl inside to be faced with a threatened snake or something.
So... presently, I am leaning toward doing a roof of painted plywood where every other panel is attached on hinges. My reasons are:
* The slope of the roof should easily repel rain.
* Precipitation is very light under those trees.
* This is a rental property, so this structure only needs to live 2 - 5 years.
* The roof overhang would help protect the cheap particle board wall coverings.
Gotta finish this weekend. Cold air has arrived, and I suspect it is stirring predator appetite. My canine / feline security staff is less concerned with guarding the birds and more concerned with snuggling in warmth.
OK - I just checked out the billboard tarps. That is now a consideration. The size I need is $75 unless I cut and glue (apparently an option). I am now seriously considering this option. This is for a lighter weight tarp - but $30 for shipping.
Hmmm - they serve as pond liners too. That could make a purchase of a larger tarp more worthwhile.....