What did I learn while building the balloon?
A lot. Even without flying, I learned quite a bit about ballooning. There is no part of that system I don't know how it works. No part I can't fix. I wouldn't even rule out doing it again.
I also learned I don't have nearly as much time as I thought I did. It took me 18 months to find a free 360 hours for construction. That doesn't include the time spent in design and documentation. That 18 months saw changes in my job, the death of my mother and grandmother, the birth of my first child, the start of construction for a new house, the re-marriage of my dad, and the first wrinkles on my face. (I'm not even thirty. If I build another balloon I'm sure I'll have gray hair.)
There were several months I did no work on the balloon at all, and just paid attention to my family. Many evenings I yearned to go back and work on the balloon, but did stuff around the house. There were days the neighbors complained about the unmowed grass while I worked upstairs. The established strawberry patch and asparagus patches were lost to weeds.
What was always hard was to be out with my family and see balloons in the air. I couldn't fly, and I wasn't getting any close by not sewing.
If you are thinking about building a balloon, remember that spending time with your family and not your balloon isn't a sacrifice you make. That may seem obvious, but that logic unfortunately leads to the fact that you made no sacrifices during the building process while your family was always the one that did. No matter how many months you didn't work on the balloon.
All told, I enjoyed the process, and I'd do it again.