Writing Postcards with a 3D Printer

I 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.