Although 3D printers are the go-to 'cool' small-scale manufacturing device of the day, they're not without their problems: at the hobby level, they're slow, often finicky to set up, and can suffer from weak finished parts due to poor adhesion between the built-up layers. For these reasons, and a bunch more, we at oomlout prefer our tried-and-tested laser cutters - and so does Martin Raynsford. Having found that knobs constructed on a hobbyist 3D printer were proving weak, he turned to another tool and designed a laser cut knob. Constructed from an acrylic core, for strength, with a wooden outer to make it comfortable to hold, the knob is stronger than its 3D-printed predecessor and can be produced more quickly. While it's true that laser cutters are typically more expensive than 3D printers at the hobbyist end of the spectrum, most hackspaces have a cutter for their members' use while DIY laser cutter builds and small-scale units are constantly dropping in price.
Wood is nice to hold but it shears off pretty quickly so I used a mix of wood and acrylic. The acrylic core runs vertically and absorbs a lot of rotational torque, the square and shaft also mates with the Z shaft well. The knurled top of the knob makes it easy to grip.