A personalized mRNA vaccine has shown promise in treating melanoma, with promising trial results suggesting that cancer vaccines could be used to target other tumors.[2297][2306] People older than 100 have been found to have more cancer-killing cells, a discovery that could potentially lead to longer human lifespans.[2307] Researchers are using 3D printing to create custom lab tools, which can be cheaper than buying them, and are exploring its potential in the field of exoskeletons.[2347] Scientists are probing underground geology using 'thunderquakes' that generate acoustic waves, providing new insights into the Earth's interior.[2291]