On our recent summer family holiday, I stopped in at The California Academy of Sciences, a beautiful science museum and research facility in San Francisco. In the gift shop, I grabbed a MetalWorks laser-cut trolley-car kit. MetalWorks are 11cm square sheets of tin, laser-cut and laser-etched to come apart into pieces ready to assemble into models of famous buildings, iconic vehicles, and other landmarks. I cleverly threw away the packaging (including the instructions) when we packed for home, but as I just discovered when I sat down to assemble the model, the company is smart enough to post PDFs of their instruction sheets. The model was just the right amount of challenging for me — the kind of thing I could do in 20 minutes with a pair of tweezers while carrying on a pleasant conversation, and the finished product is a pretty cool-looking model indeed.