Old Geezer hobbies are hobbies you adopt when you become an old geezer. The hobbies themselves may be for any age, but the old geezer started doing them later in life.
For me, they include: building and equiping a freestanding woodshop so I can do fine woodworking, not just simple home and car repair out of the garage; scratchbuilding and flying r/c model aircraft (goes with the woodshop); landscaping a backyard with gazebo, vegetable/herb garden, flowerbeds, and even a compost heap hidden way in back (previously either rented a house or owned a condo, so the first yard of size at 25,000 sq ft [.6 acres] that I could do something with); converting my Jeep into a real offroader with skid plates, beed lock rims and real offroad tires, rock rails, offroad lights, roof rack with full size spare and emergency supplies, etc.
Well, those are my old geezer hobbies. For the other old geezers in the group, what are you new hobbies you've adopted of late.