A hand-powered centrfuge based on models from the Prakash lab at Stanford and David Eccles at GrinGene. There are a number of safety concerns associated with spinning 1.5g tubes at 7000 RPM, so I have made a few design changes to address these problems. (1) A locking-lid has been added (2) Sharp edges have been removed by camphering to prevent string abrasion and user harm (3) string holes have been placed further away from the rotational axis to increase angular velocity. The cover should be placed on the centrifuge after tubes and collers have been inserted. The correct lid orientation is  90-degree edge facing down, camphered edge facing up. A dowel, locking pin, or bread tie can be used to secure the lid. Based on laser tachometer measuremnets this centrifuge acheives ~3,500 RCF if you're really going for it. The average angular velocity can be increased by using a longer string. We used ~1m of 135 test braided fishing line.