I was in my office and working with staff to determine if something could fit.  I had my caliper with me in my computer bag.  Unfortunately, I left it in my office and I wanted to use one at home for K-Cup holder I was designing.  So I decided to design a caliper and print it.  (I did purchase two more so this will not happen again.  I also have five multimeters for the same reason.)  

While it worked fine, it was not the best design.  When I finished my K-Cup holder I went back to redesign this.  A few changes, a few prints, a few more changes and this is what I have.

It goes from 0 to 95mm with markings every 5mm.  While not the most detailed, it's easy enough to determine the general size of something.  And this thing can be accurate depending on the accuracy of your printer.  Obviously, it would not be used to design a spaceship, but fine for a few of the things we design for 3D printing.  The inner part has a block so the caliper does not pull out all the way.  And you can print one for less than 70 cents of filament!  This is an easy print, and usable if you follow my printing instruction below.  PLEASE FOLLOW THEM.

Like most of my prints here, I designed this for my own use but felt that someone else could find value in it.  It prints in place and requires no supports.

I included the STEP file along with the STL file.

The first two pictures are renders in Cinema 4D, the next two photos are of an actual print, and the last one is a render showing the direction to tap it against a hard surface to free it up after printing.

Printing Instructions

This should be printed in PLA.  At first I thought printing this in ABS, or any other material that shrinks, would not work.  But I tired printing it in ABS and it was fine.  Where PLA required a tap on a table to free it up, ABS needed a few hard hits before it was free to move.  I would not recommend PETG since this material often has some stringing issues and not recommended for small details.  Additionally, you need to have a printer that does a very good first layer or it may fuse together and not work.  

I successfully printed this at a layer hight of 0.15, but I had much better results at 0.12.  The tolerances are very tight, so 0.20 is not recommended.  I used a 0.4mm nozzle without any issues.

You should not use any support material.

When the print is complete, the two parts will most likely be slightly fused together,.  This is fine.  A slight tap on a workbench will free it up with a satisfying snap.

Final Thoughts

By no means is this designed to replace even a cheap caliper.  But really, using 70 cents of filament makes this very inexpensive.  I'm pushing the details that a 3D FDM printer can do, so there is no room for mm markings.  This just has cm and half cm markings.  In all honesty, a using a ruler make make more sense, but this is 3D printing.

I printed a bunch of these with sample filament, and all brands seemed to print fine.  My Prusa MK3s+, MK2.5s, and FLSUN printed these perfectly.  I also tested it on and Ender 3 Pro and I had no luck, it would not print right no mater how much I tried to adjust the first layer.  It's possible that the old nozzle is worn and printing a little more than 0.4mm, I don't know.  My Ender 3 Pro is scheduled to be parted out soon, so I'm not going to bother changing nozzles to see if that was the issue.

Good luck with your 3D printing!