Finley asked me for help putting a proper desk in her fort, so I had her draw me a picture of what she wanted so that we could plan things out. Her idea was elegant and made a lot of sense, and after I suggested a counterproposal we decided to go with her original plan, using lumber and materials we had around the house.
Finn and I hit the store for the two things we needed: a pair of strong hinges and some chain. The key to the desk was that it needed to be collapsible, as space in the fort is at a premium. I cut a crosspiece down and we roughed in the height, and after we picked up a friend who wanted to help, I had them install the hinges and put the chain in place.
Once that was done I cut two pieces of scrap wood and made a simple latch for the stowed position, and voila! She has a usable desk next to the window.