The oxyacetylene torch is always fired up in Oakland, the heart of DIY culture. The maker community is super strong; and, there may very well be an abnormal amount of sewing machines, and mechanical pieces waiting to be fixed, assembled and retrofitted. Add onto that a serious urban farming culture where homesteaders are rabid for classes on backyard chickens and apple-tree growing.
Check the event calendars at maker and entrepreneurial hubs like 25th Street Collective, American Steel Company, Impact Hub, Rock Paper Scissors Collective, and The Crucible. Often they have one hour or one-day classes (or much longer). Am Steel, for example, hosts the nationwide phenomenon of Swap-O-Rama-Rama; participants bring in clothes they no longer wear, swap them, then modify them at sewing machines or silk screen stations. Rock Paper Scissors teaches the simple (how to make lip balm) to advanced (DIY animation). The Crucible lineup is always slightly jarring and Oakland-ish, with lessons on fire dancing and how to make your bike desert-ready. But be boring and sign up for glass blowing, or Clay Together: Parent & Child. Classes vary in length.
Onto something more delicate. At the Institute of Urban Homsteading, you may find something like the famous California crop of avocados as the focus of a four-hour class, or composting. One of Oaklands most famous homesteaders, author Novella Carpenter, lives in West Oakland and periodically opens her Ghost Town Farm for a variety of classes like tomato canning and backyard chicken tending. In Old Oakland, The FloraCultural Society, which specializes in flowers grown before the 1920s, focuses on plant-based lessons like dying flax and arranging bouquets.
If you ever wanted to be in the circus, Trapeze Arts in West Oakland lets you live your dreams, at least for an hour or two. Sign on for a single lesson in contortion, or trapeze--popular for corporations on off-site retreats. Can you trust that guy who sits in the next cube? In a similar vein, the Kinetic Arts Center offers circus-like classes but bills itself as an alternative to the gym. So instead of the treadmill, why not hand balancing?
Up in the Oakland Hills at Chabot Space & Science Center, telescope-making is on tap for Friday evenings. On Piedmont Avenue, at least two of the shops pass on their wisdom. Sew Images teaches a 3-hour basic sewing class while vintage shop Rare Bird does DIY terrariums, mosaics, figure drawing and even how to teach a DIY class.