Engineer’s Pen (Click Pen+Caliper)

Engineer’s Pen – The Everyday Caliper

A compact writing instrument with an integrated 0–100 mm caliper scale, combining precision and practicality in a sleek, retractable design.

This tool is perfect for engineers, makers, or anyone who appreciates purposeful tools. Whether you’re sketching ideas, taking quick measurements, or just showing off your clever everyday carry, the Engineer’s Pen has you covered.

This pen was inspired by a promotional giveaway I once received, a pen with a basic caliper scale. It stuck with me. As someone who often gets asked to 3D print things, especially replacement parts or spontaneous design ideas, I always carry this pen.

Even if there’s no proper measuring tool nearby, I can quickly get a rough measurement and sketch things out on the spot. It’s not just a pen,  it’s my mobile idea-capturing tool.

Key Features

• Retractable click mechanism – Just like your favorite ballpoint
• 0–100 mm caliper scale – Handy for quick checks and reference
• Precision-tuned design – Functional, accurate, and great to hold
• Printed insert template included – Trim your ballpoint refill to 98 mm
• Uses standard pen springs – Compatible with Bambu Lab’s 0.4x5x40 mm spring
• Assembly made easy – Reference the exploded drawing for clear instructions

Print Settings

• Material: PLA
• Layer height: 0.12 mm
• Top layer line width: 0.3 mm (for crisp scale detail)
• Supports: Minimal – be careful when removing them to avoid damaging small features
• Clean the build plate thoroughly before printing, crucial for bed adhesion

Assembly Guide

1. Print all parts, make sure your build plate is very clean to ensure fine detail and good bed adhesion
2. Make sure to remove all residues left behind from the supports, otherwise there could be fitment issues and the body could be damaged when inserting the cap.
3. Cut a ballpoint insert to 98 mm using the included printed template
4. Insert a spring, either from a standard click pen or the Bambu Lab spring (40 x 5 x 0.4 mm)
5. Assemble using the exploded CAD drawing as a reference
6. The mechanism might need some wearing in. (Use some lube or oil when the mechanism doesn't work smoothly)
7. Done – ready to write and measure!

Notes

While not a precision instrument, the Engineer’s Pen is incredibly useful for quick reference and on-the-go measurements. Whether at your desk, in the workshop, or on a walk, it’s always ready to help you capture ideas when inspiration strikes.