Calibron Twelve Block Puzzle (Calibron 12)

by profhankd, published

Calibron Twelve Block Puzzle (Calibron 12) by profhankd Jun 20, 2016
0 Share
Download All Files

Thing Apps Enabled

Order This Printed View All Apps

Design Tools


Liked By

View All

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag.

Print Thing Tag

Thing Statistics

875Views 153Downloads Found in Puzzles


The Calibron Twelve Block Puzzle is an apparently simple bin-packing puzzle credited to Theodore Edison in 1933 and originally marketed by his company, Calibron. The goal is simply to arrange all the pieces so that they form a rectangle (hint: make a 56x56 unit square). However, difficulty of this puzzle is rated 5/5!

There have been a lot of variants of this puzzle; in fact, there's one on Thingiverse as I write this -- but don't look at that because it shows the solution. My Calibron 12 was designed from scratch to take advantage of what 3D printers can do. The raised dimensions on each "block" are accurate in units of 2mm (with allowance for printing tolerance), so the puzzle fits in a 3D-printed box that is less than 3"x2"x1" -- but the pieces are big enough to handle easily.

Print Settings

Printer Brand:









Doesn't matter




A very easy print unless the pieces don't stick to the bed -- consider printing with a brim. The version shown here was sliced using Slic3r (so the surface fill pattern could be oriented to look more like wood grain) and printed using 0.25mm PLA. It takes less than 2 hours to print everything on my M2. You might be able to fit everything on your bed to print in one shot, but I've also provided separate STLs for the pieces and the box in case you initially don't want the box or stuff doesn't fit all at once.


No post-printing work is needed. However, the sample shown has the tops of the markings on the "blocks" blackened using a permanent marker.

How I Designed This

This was designed from scratch using OpenSCAD. However, the part dimensions are widely available. My primary reference for the dimensions was actually this code which claims to solve the puzzle. No, I'm not going to show you the solution... I haven't solved the puzzle myself (yet). This is also why I didn't pack the pieces optimally on the printer bed -- don't want any spoilers now, do we?

More from Puzzles

view more

All Apps

Auto-magically prepare your 3D models for 3D printing. A cloud based 3D models Preparing and Healing solution for 3D Printing, MakePrintable provides features for model repairing, wall thickness...

App Info Launch App

Kiri:Moto is an integrated cloud-based slicer and tool-path generator for 3D Printing, CAM / CNC and Laser cutting. *** 3D printing mode provides model slicing and GCode output using built-in...

App Info Launch App
KiriMoto Thing App

With 3D Slash, you can edit 3d models like a stonecutter. A unique interface: as fun as a building game! The perfect tool for non-designers and children to create in 3D.

App Info Launch App

Print through a distributed network of 3D printing enthusiasts from across the US, at a fraction of the cost of the competitors. We want to change the world for the better through technology, an...

App Info Launch App

Quickly Scale, Mirror or Cut your 3D Models

App Info Launch App

Treatstock is an online platform that offers decentralized manufacturing services such as 3D printing and CNC machining for business-to-business and business-to-consumer sales all over the world. W...

App Info Launch App

3D print your favourite design with NinjaPrototype, a professional 3D manufacture with consistent quality and speed.

App Info Launch App