I love custom made elements on my enclosures and I also love to reuse or hide memorable used objects in my creations that would otherwise just collect dust. Recently I recycled some wood from the old garden chairs from my parents house. The chairs were old, unusable and certainly not "en vogue". But they were the chairs I spent a lot of happy childhood moments on and I am glad to have found a way to preserve these memories by reusing some of their wood in a project and not having to keep the chairs themselves.
I find poti and fader knobs are a great way to give DIY-creations a very personal touch and to "hide" such memorable gimmicks that tell a story. They are often in plain sight and even touched frequently. Reason enough to give those elements some thought in my opinion.
With this little report I want to share how I managed to use almost every object as a poti or fader knob. In fact anything that can be drilled and glued will work. I'm covering only potis with a rippled shaft thoug, as I found them to be most problematic. Knobs for these potis (and faders) work simply by friction and I didn't quite succeed at drilling holes with just the perfect fit (loose enough to be taken on and off while still tight enough to be safely turned). Not all materials would even be suitable for that perfect "friction fit" - wood will wear out while metal is too smooth.
What I came up with is to 3D-print sort of inlays that feature the same ripple pattern as the poti shafts and can be glued into easy to drill holes (say 8mm). The 3D-printed material (PETG in my case) provides good fricition and some flexibility at the same time to allow for a perfect fit. The plastic is not visible from the outside and only serves as an adapter between shaft and knob.
I glue those 3D-printed inlays with 2K epoxy glue into the knobs, which will keep them in place forever and works on almost every material.
Here's another example for fader knobs made from oak with a brass inlay:
