I wanted a simple and secure way to hold a pencil for a project and I came up with this idea after looking at some Japanese joinery. At the end my project didn’t need the pencil but I thought the method would be useful so here it is:
I sketched it for 3mm plywood but you can use the idea for the material thickness and pencil size you want. The wedge will let you adjust for some pencil variability but you can size it to your specific pencil for a tight fit.
And the SVG for 3mm plywood:
5 degrees for the slope of the wedge seems to work quite well both for holding firmly and for allowing you to remove it. But I’m sure there is an ideal angle to be found with further research. I hope this helps add a simple feature to one of your projects.