[Bill Hammack], aka the [EngineerGuy] is at it again, this time explaining how retractable ballpoint pens work. In this excellent video, he describes the simple (but remarkably sophisticated) ...

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[u407]’s 3D printed Signspinner was created as a clean/dirty indicator for a dishwasher, and at its heart is a mechanism that works a lot like that of a retractable ballpoint pen. Every click of the ...

To achieve the satisfying look of an error-free written page, an erasable pen is a must-have. The best erasable pens write smoothly and erase cleanly without leaving residue or tearing pages. Erasable ...