Mechanical Prototyping Pencil




About: Electromechanical Engineer, Product Designer, Maker. I love to make prototypes and teach others in the process. I graduated from UCF and spent two years working at NASA.

This is a 3d Printed attachment I designed that transforms an ordinary mechanical pencil into an awesome wiring pencil for prototyping. It was inspired by the old school roadrunner and verowire wiring pencils. The wire is 0.5mm magnet wire with an enamel that melts away with the heat of the soldering iron so there is no need for stripping wires. To use it, simply advance about 0.5" of wire and hold it to the solder joint until the enamels melts back. Once the solder hardens, click and drag to your next solder joint. I like to use tweezers and snips like in the video. You can even use thin solder to make a soldering pencil to go with your wiring pencil. Hope you guys like it!

Step 1: What You Will Need

1. Paper Mate Clear Point 0.5mm Mechanical Pencil

2. Magnet wire with solderable enamel. Diameter of 0.5mm or less.

3. 3d Printed Parts

4. Any nut and screw with 0.2" diameter or less. Length needs to be at least 1 inch.

5. Glue. Super glue(cyanoacrylate) or hot glue will work.

Step 2: 3D Part Files

Step 3: Assembly

Download and 3d print the files. Make sure to print two spool halves. Once done, glue the two spool halves together using super glue or hot glue. After the glue dries, wind the magnet wire around the spool. Insert the pencil clip into the spool holder and attach the spool with a screw and nut. I recommend using a chicago screw but any screw will do. Attach to the pencil and prototype your heart out! You can even use thin solder to make a soldering pencil to go with your mechanical prototyping pencil.

If you like my project, please vote above for the contests and please subscribe to my YouTube Channel to see more of my projects!

Thank you!



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24 Discussions


3 years ago

Is your Spool Holder model a solid piece of plastic? It could be printed more cheaply if it were hollow. I'm getting an estimate to print this, and it's by far the most expensive part (about $12 compared to about $3 for the other two parts).


3 years ago

Thats cool, these pens are extremely expensive if you want to buy one.


3 years ago

Long ago and far away (when I was working in Germany) we had wire for making prototypes that had a plastic-like insulation that shrank back away from heat (it was also tin plated which helped). I've heard about using magnet wire like this but wasn't sure which kind to get -- wanting to be sure that I don't end up with pounds of wire that won't work. Where do you get your wire? This prompted me to do a quick search and (lo and behold) Newark has 4-packs of 38ga for $20-ish. Search for ROADRUNNER RRP-A-105Wire. They also make a 36ga wire but Newark doesn't have it. The 38ga wire is tiny -- only 0.174mm. There are many gauges on EBay as well I see. What gauge do you use?


3 years ago

Holy bleeping cool! I'm as impressed as hell! Very inovative. Like wire wrap pn steriods & twice as cheap yet so simple to use. Thanks much!


3 years ago

This is absolutely delightful. Have you tried this with a 0.7 mm pencil? Seems like the larger diameter would be useful as well.

1 reply
Proto GAlphatrion

Reply 3 years ago on Introduction

Thank you. I chose 0.5mm because I had 0.5mm magnet wire on hand. 0.7mm will not work with 0.5mm magnet wire, but if you have 0.7mm magnet wire then go for it. The larger magnet wire you use, the harder it is to remove the insulation with heat.