Reuse an old tree to make a log pathway in your garden. Good use of "yard" trees and other wood that can't be milled; works much better in climates without termites. Good drainage under the log rounds will make the path last longer.
If you have the space, make a cozy cabana to put in your back yard. First build the frame using PVC pipes. Then dig the foundation holes. Add the legs and, at the end, add the curtains. You can customize this project however you want.