I have not done this in a while, but I thought it was pretty cool....

Japanese paper folding... Origami

Watercolors are fun. But, acrylic might be easier because you could put the painting on an easel ... watercolors usually are done flat to keep the paint from running. Bob Ross taught a style that people with almost no talent can do. I am sure libraries would have books on it. Oil is easier than acrylic, but more fumes, more cleanup.

Crocheting is not very "masculine" but it is fairly easy to learn, and you can make great shawls, afgans etc. without to much training.

Calligraphy! Italic writing.... you can make some good money doing wedding invitation envelopes too! I used to before I got my hand slammed in a car door and lost my dexterity! Used to get $1 per envelope... The book I used was "the italic way to beautiful handwriting" and I just got paper called onion skin and paper clipped it over the text book to practice instead of using the book itself.. that way I could practice more times.

I'll try to think up a few more....
Jules