Pretty much made it up as I went along (here's
the story) We walked back in our woods (we've got 5 acres here, about 2/3 woods although we don't go back there much because it can be swampy and is absolutely covered
in poison ivy) and discovered where Ivan had blown over our two huge swamp oaks
. DH chainsawed off a couple of the branches for me. Pretty much had to design the shelves around the branches since no two are identical. When I went to put in the additional support I lucked up with a really weird branch section from a scrub pecan tree that I had DH cut down (tired of mowing around it.) That's the section that has a branch going off at almost a right angle to support the second shelf from the top I believe. I had thought I was going to have to put in a huge ugly brace on that particular shelf but now it's extremely sturdy.
After we let them out of the bedroom when we got done moving it from the den they went to it immediately, first pretty much cautiously sniffing. "Hello! This wasn't here earlier!" But it only took about ten minutes before they were climbing up the various levels although they still haven't quite figured out the best ways up and down. At the moment the tendency is to take a flying leap
from whatever shelf they're on at the moment to the floor although I've designed it to be stair-steppable. Hopefully that behavior will stop as they figure it out (and before they get too big!