Manual Calliper

3D Printed 2-Part Manual Caliper – 100mm & 150mm Versions

A simple, affordable and surprisingly accurate measuring tool designed for everyday workshop jobs, engineering tasks and classroom use.

I wanted to make something cheap, practical and accessible for everyone. Each caliper costs less than 50p to print, making it ideal for schools, makerspaces, workshops and anyone who needs a handy measuring tool.

What's Included

Two versions are available:

• 150mm / 6-inch version: Uses a standard 150mm metal ruler.

• 100mm version: A shorter, more compact alternative that is cheaper and more versatile for smaller jobs.

Both designs are made from just 2 printed parts, keeping printing time and material costs to a minimum.

Features

• Designed specifically for a 0.6mm nozzle.

• Engineering-focused design with accurate measurements.

• Two measuring functions:

  • External measurement – 0mm starting point.

  • Internal measurement – 2mm minimum.

• No depth measurement function.

• Can be mirrored for left-handed or right-handed use.

• Lightweight, affordable and easy to assemble.

• Open-source design for makers, teachers and students.

Printing & Assembly

• Parts: 2

• Print time: Approximately 23 minutes per part. No Supports needed

• Estimated print cost: Less than £0.50 per caliper.

• Recommended materials: PETG or ABS for better durability and longer lifespan.

• Recommended nozzle: 0.6mm.

Assembly instructions:

1. Print both parts.

2. Clip the two printed parts together.

3. Slide the 100mm or 150mm metal ruler into its designated slot.

4. The ruler is held in place using a loose tolerance fit.

5. If preferred, use a small amount of UHU glue to secure the ruler permanently.

You'll need to purchase a standard 150mm or 100mm metal ruler. Temu and AliExpress are good options if you're looking to keep the overall cost down.

Design Notes & Development

I originally designed this as a left-handed tool but decided to make it suitable for both left- and right-handed users by simply mirroring the model.

I also experimented with a magnetic version, but it wasn't secure enough. The magnets also tended to rub against and damage the markings on the ruler, so I went back to a simple mechanical fitting.

I wanted to make something genuinely useful that I could give away to my students and share with the wider open-source community.

The design is intended to remain accessible to everyone: makers, teachers, engineers and hobbyists.

I've technically branded the design BGK to help identify the original model. I'd love to see people printing and using it, but I'd hate to see it copied and resold on platforms like Temu without credit to the original design.

Made for makers. Designed for the classroom. Shared with the community.

Enjoy printing!