I feel like we're reliving the late 1790s again, back then you had Ramsden figuring out how to divide the circle into into seconds of arc, taking the marking of scales from an artform into something that could be manufactured reliably. Maudslay with his thread cutting lathe took the making of screws from a manual process pawned off on apprentices to something that that could be done in mass production. Wilkinson's boring machine made it possible for Watt to build a pressurized steam engine.

All of these tools are based on things that were one-offs of earlier efforts, and turned into practical machine tools by someone that history chose to remember. We're now at the point where making things by manipulating individual atoms is something a determined amateur can do, it's amazing!

I find myself fascinated by the Wyler Inclinometer, which uses a thin copper disk with spiral arms as the basis of a differential capacitor, and when complete, resulting in a device that can used to calibrate a granite surface plate. It can typically measure 1 micron/meter of deviation.

We now have 3d printers that can reliably make almost anything you want by fusing filament, or stereolithography, or fusion of metal powders. You can buy desktop 5 axis CNC machines. There are control systems available to let you build almost any type of machine tool you can imagine, in as many axis as you want.

We've got software defined radio, cheap atomic clocks, transistors that can switch megawatts, all within reach of a hobbyist.

What an amazing time to be alive.