A little carpet adhesive, a few staples, a handful of small brackets, and it's almost complete! Overall, it's solid as a rock and has enough mass to keep it stable without anchoring it to any walls.
Only things left are a ramp from ground level to the second story across the front and potentially a hammock somewhere(I'm struggling to see where i could put one without compromising some other useful part of the tree).
Thoughts are welcome!
