Sorry to hear about your problem w. Lyme's disease. I knew it caused severe fatigue symptoms, but not loss of memory.
3-d work is not too different than 2-d. Perhaps working on carving will bring back some of your graphic skills. Most likely, you will still need to envision what you are about to carve, and how to position your tool for the cut. No worries about color space, or resolution. No considerations about page layout, but still a need to watch for proportions within the carving area.
The problem w. dead sticks is that sometimes there are internal flaws that are not evident on the outside. My test for stick strength is to ram the stick into soft earth, as if I was falling forward. If it doesn't flex too much, or worse, shatter, I figure its OK for a walking stick.
