3D printers have been around for a while now, but I feel like they have really become more mainstream technology in the last 5 years or so as prices have come down.  I think of it as similar to CNC where you might take a digital file and mill down a block of metal, a subtractive process.  3D printing is just the opposite and is an additive process where you are laying down layers of molten material, usually a type of plastic, to create your shape from a digital file.

My sons turned me on to YouTube a few years back which is where I primarily learned about 3D printing.  Once the pandemic hit and my work commute became zero I decided to invest some time and learn how to use a 3D printer.  It is a bit of a slow process and requires some babysitting, but it has worked out well.  Then, once I got comfortable printing existing downloadable files I dabbled in designing my own creations, which I find very satisfying.