# Laser Cutting a 3D Pyramid Puzzle ...

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## Introduction: Laser Cutting a 3D Pyramid Puzzle ...

Hi,

Okay, first we need to describe the puzzle;  It's about a 4,000 years old design.  It's very simple ... two exact halves of a 3-sided pyramid.  Sounds easy?  Well it's a brain teaser for your friends to assemble the two pieces into a pyramid.  This Instructable is my challenge for you to see what all materials you can use for making these puzzle pieces using laser cutting.

The 40W laser prize here is a perfect home model for making soft plastic toys ... so first you need to find a suitable material (NOT PVC, NOT Lexan, NOT Stone etc... for various reasons of poisoning yourself and viewing friends 'n family to the fact that 40W can't cut into stone very well.)  But what about a block of acrylic?  That might work if the acrylic isn't too thick ... or maybe just using a chunk of Styrofoam packing to reshape into your puzzle pieces (near zero materials cost!) ... the cost is just a few calories of energy you use to cut it into small enough blocks to fit into your laser cutter/engraver.

Okay, lets get down to the meat of this Instructable ... Lets make a 4,000 year old Pyramid Puzzle piece.

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## Step 1: Selecting the Proper Size to Cut ...

My SolidWorks sketches are for 3D Printing, but they're also small enough for laser cutting soft materials too.

The idea is that the length of one side of the pyramid becomes the maximum depth of the laser cutting required to make these puzzle pieces.  My experience with a 45W laser tells me I can easily slice through 60mm of Styrofoam so I'll stick to my original dimensions to keep this Instructable easier to modify for your own pleasures.

So the length of one side of the pyramid is 60mm ... then the center square of one half of that is exactly that 1/2 or 30mm x 30mm

The height from the bottom of the material block to the outer edge of the pyramid is 20mm ... that is from the center of the pyramid to the outer edge of a corner is 20mm.  You'll see this more clearly in the next step.

This tells us that the block of material needed to make this puzzle piece needs to be something greater than 60mm x 30mm with a flat bottom and at least one very important flat side to sit on the laser cutter cutting bed.

Now we start with our first of two cuts (two cut sketches you make yourself) ... the two ends of our puzzle piece.  You can see that in the 3rd image labled PyramidPuzzle-02 so now it's your turn to sketch that cut out in your lasers design program (CorelDraw, Adobe Illustrator ...)

Then place the material into the laser cutter and make the two cuts.  Keeping the left over material still in place on the side that has the very important flat surface ... because that's used for the next cut!

## Step 2: 2nd Laser Cut ... for Pyramid Puzzle Pieces ...

Okay, we have the two ends cut out nicely, now you stand up the block of material on the flat side (end of the pyramid piece) so we can make the next laser cuts to finish the cutting.  Yes, that's all it takes ... really just two cuts and you have a neat little 3D Puzzle Piece.

So using your sketching software (Again, I used SolidWorks myself) you then make the cuts just as they appear in the image PyramidPuzzle-04 ... it's so easy, like chopping off two ears of a head ... but in this case it's just the squaring material of the pyramid block.

When the laser cutting is done and you've removed the excess materials from the puzzle piece it should look like image PyramidPuzzle-06.

## Step 3: Assembling the Two Puzzle Pieces ...

Okay, this is the puzzle ... to assemble the two pieces into a 3-sided pyramid.  It's easy, but is a brain teaser.  I suggest you try it yourself before learning the secret to how the human brain works.

DO NOT SCROLL DOWN UNTIL YOU HAVE TRIED THE PUZZLE YOURSELF!

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Okay, now here's the brain teaser ... the human brain likes to fill in the blanks, make things parallel and symmetrical but to build the pyramid from two exact halves requires you to turn the two pieces 90° opposite each other ... simply fit the two 30mm x 30mm square surfaces face to face ... then turn the two pieces 90° opposite each other and you got your pyramid. You can see this in image PyramidPuzzle-08 ... It's so easy! ha ha ha ...

## Step 4: 3D Printing ...

Okay, so those that also have access to a 3D printer ... here is the piece .STL if you're too lazy to sketch the part yourself, but I really recommend at least watching my short RoboToons animated cartoon showing how to design the part using SolidWorks and then translating those simple steps into the 3D CAD program of your choice ...

Please also visit my RoboToons website;  http://www.brainless.org/RoboToons/

You can see the results from a short 3D Design class I taught for some boy scouts here;

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