Bay seniors seeking hobbies never dreamt of at summer camp have plenty of options here. How about making your own wooden six-pack holder at the woodthumb in the City. $65. They are also a retail outlet with witty wooden items like ties and sunglasses. Into leather? The workshop in San Francisco will show you how to dye and create your own leather belt (while belting down brews) on June 9. $72. Oft-mentioned in the Geezer are the classes at Oakland’s Crucible includes blacksmithing, glassblowing and neon sculptures.