GoKawiilI read Amy Goodchild’s blog post about digitizing her handwriting in JavaScript a while ago and couldn’t stop thinking about it. I didn’t end up digitizing my own handwriting, but it pushed me toward a smaller idea: clamp a ballpoint pen to my 3D printer and let it write postcards for me.
This post is the story of getting there, including the part where my printer almost drove the pen straight through the bed.
The pen adapter#
I have an Elegoo Neptune 4 Plus. The first job was a way to mount a pen on the extruder, so I designed an adapter in OpenSCAD and printed it in PLA. It comes in three pieces.
The main adapter body, sliced open in OpenSCAD. The channel holds the cartridge and the spring sits above it.
The main piece wraps around the extruder and holds the ballpoint cartridge and a spring. The spring matters more than I expected. It lets the pen push down a little into the paper, so there’s enough pressure to write even if the surface isn’t perfectly level.
The second piece is a small U-shaped part that presses against the top of the extruder. Without it, the screws holding everything together would bear directly on the extruder, and I didn’t want to risk that.
The third piece is a tiny clamp that keeps the cartridge spring in place.
The ballpoint cartridge and the little clamp that keeps its spring in place.
None of the parts are precise. PLA was fine, and I’d guess almost any filament would work. If you want to print your own, the STL files are on Thingiverse.
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