These are extremely lightweight and the sides of the hexagon are glued together.  The largest piece was damaged where the glue had separated.  It definitely was not solid pine.  It felt like balsa wood that had been treated to look like pine.  I was able to repair the broken section by carefully hammering in two long nails screws just caused the edges to split.  But once I was done, I realized it wasnt worth putting holes in my walls for something that would almost certain collapse from any added weight, so I ended up using the middle and large sizes as cat beds.  Better than nothing 

But overall this was an extremely disappointing purchase.