You might think that if you dug some tunnels down into the ground where you could be out of the sunshine, that you might find them to be relatively cool …read more (https://hackaday.com/2026/09/29/geothermal-cooling-for-new-yorks-subways/)

Electromechanical TV Goes 3D with This Light-field Display
https://hackaday.com/2026/09/29/electromechanical-tv-goes-3d-with-this-light-field-display/

A mechanical TV — the kind that makes an image with a Nipkow disk and a single lamp with some help from persistence of vision — is easy enough to …read more (https://hackaday.com/2026/09/29/electromechanical-tv-goes-3d-with-this-light-field-display/)

Improved Double-Sided Toner Transfer Method
https://hackaday.com/2026/09/29/improved-double-sided-toner-transfer-method/

In the era before PCB shops would make almost any PCB imaginable, as well making many other manufacturing processes for prototypes available to hobbyists, there were several ways of making …read more (https://hackaday.com/2026/09/29/improved-double-sided-toner-transfer-method/)

Designing a Fully 3D-Printed Mechanical Calculator
https://hackaday.com/2026/09/29/designing-a-fully-3d-printed-mechanical-calculator/

Even if almost tragically impractical in a world where digital calculators are cheap as chips, mechanical calculators and their big mechanical computer brethren remain an absolute marvel of engineering. Using …read more (https://hackaday.com/2026/09/29/designing-a-fully-3d-printed-mechanical-calculator/)