I thought I was a fairly apt DIY'er, but then I saw this next-level achievement. This man built his own lens from scratch, right down to machining the glass himself.
Mats Wernersson took the classic Petzval lens design, notable for its swirly bokeh that makes it an interesting portrait option, modified it a bit, then hand-built his own lens with only the lens mount, diaphragm blades, and helicoid being premade. This included fabricating the barrel and all metal parts, but most impressively, grinding and polishing the optical glass himself. The result is a 90mm f/2.8 lens, which, just like the classic Petzval, shows a more pronounced effect as the aperture is opened. It's absolutely fascinating to watch the process, but I have to say I'm even more impressed by the sample shots at the end. I used to own a Petzval lens, and these shots were extremely reminiscent of its output, but with an even more pronounced swirly bokeh effect. Manufacturing optics is a high-precision process, so to see it done by hand so successfully is all the more impressive. Also, I have to admit that I found the red ring to be a fitting touch.
[via No Film School]