Category Archives: Mathematics

Pi Pie Trivet

Pi (squared) trivet - 9

Happy Pi Day! Pi day was just made official. In honor of National Pi Day, we present a pi trivet, perfect for cooling your Apple pie (or pi pie) on.

Pi (squared) trivet - 6

Besides just the letter pi, The number pi up to the first thousand digits after the decimal are laser engraved into half-inch thick cork. The overall size of the trivet is about seven inches, square.

Pi (squared) trivet - 2

This cork is actually gasket material from McMaster-Carr, which has a wonderfully smooth and even surface. Compared to many of the other cork materials that we have seen– like that used for many cheap trivets– this has very little pitting and the surface shows fine detail very well.

Fabric Klein Bottle

fabric klein bottle
Klein bottles are an entertaining mathematical idea–a shape with no volume. A Klein bottle is basically a tube where the inside is connected to the outside. Making a Klein bottle in our 3D world requires a bit of cheating to work, by adding a hole in one of the walls of the tube to provide a place for an intersection.

The most common physical realization is a glass Klein bottle, which you can ogle and buy at Acme Klein Bottles. They also sell wonderful knit Klein bottle hats which can be bought with a matching mobius strip scarf. I was lucky enough to be given a set as a gift, and it is cozy and bright and wonderful. My only complaint is that the narrow neck of the Klein bottle makes it hard to pull it inside out (or right side out, since it is the same thing) to play with it.

I have found that the concept of a mobius strip is more understandable when you can hold it in your hands and turn it around and around, and I thought the same would be true with a Klein bottle, if only it were a little more flexible than my hat. With that in mind, here’s how to make a simple fabric Klein bottle you can play with from two sleeves of a worn out shirt. Continue reading Fabric Klein Bottle

A single sided circuit board

Mobius Circuit - 21

In electronics, it is common to talk about single sided circuit boards. The most common type is a circuit board that only has printed wiring on one side, and components on the other side. There are also surface-mount boards, where all the wiring and components sit on one side. But aren’t all of those reallyjust two-sided circuit boards where you only put components on one of the sides?

Here we present a method of making your own authentic single-sided circuit board.
Continue reading A single sided circuit board

Binary Birthday

Binary Birthday

I am this many.

Have you ever heard of the unary number system, i.e., base-1 numerals? That’s the formal designation of tally marks– a means of representing a number symbolically by using symbols, where the number represented is equal to the number of symbols. While easy to grasp, it’s also a rather inefficient system, so we don’t find too many uses of them in modern life. One of the places that we do (almost) always use the unary system is on birthday cakes, where a birthday cake has one candle per year. This is fine for small numbers, but positioning, lighting and blowing out candles becomes impractical past a certain point.

Here’s a better way: A binary birthday candle. It consists of a single candle with seven wicks, where the wicks that are lit represent the birthday individual’s age in binary. This single candle design works flawlessly to represent any age from 1 to 127, never requiring anyone below the age of 127 to blow out more than a mere six candles at a time.
Continue reading Binary Birthday

A Sinusoidal Acrylic Bracelet Design

Acrylic Nesting Bracelets

Sleek sinusoids for your wrists. Laser-cut acrylic.
A free design from Evil Mad Scientist Laboratories, complete with dowloadable files so that you can make your own. (And isn’t this a good time for your first laser project?)

In case you haven’t been bitten by this particular bug yet, here’s a quick intro. Laser cutters are an awesome tool in the modern DIY arsenal. This type of laser is a lot like a laser printer, but uses deep infrared carbon dioxide laser that can cut or engrave most plastics. You can find these at hacker spaces like NYC Resistor and membership shops like TechShop and The Sawdust Shop, so it’s finally getting to the point that almost anyone can learn to use one. However not everyone lives by a laser shop, so sites such as Ponoko, Pololu, and Big Blue Saw offer laser cutting services and enable you to submit jobs from anywhere.
Acrylic Nesting Bracelets
Our bracelets are cut from a single sheet of acrylic (using a laser, obviously!) in concentric wavy rings to form a nesting set of various sizes. The light plays through the transparent acrylic in fun and fascinating ways.
Continue reading A Sinusoidal Acrylic Bracelet Design

20 millicenturies of Evil Mad Scientist Laboratories


Happy birthday to us! Evil Mad Scientist Laboratories is now two years of age. Collected below is a “Best of Evil Mad Scientist” for the past year: Some of our favorite projects that we’ve published over the last twelve months. Here’s to the next year!

Quick projects:

Set of bands
Rubberbands made from old bicycle innertubes.

vertical light tent setup
Light tent made from a lampshade.

Still life with yellow paper (group shot 2)
Chip bugs


Spool spinner from an old fan.

Quick C to D adapter
The $1.00 C to D adapter

Electronics projects

Weekend Projects Podcast!
How to make a Joule Thief from Make: Weekend Projects.

lights off?
How to make a dark-detecting LED night light.

The Great Internet Migratory Box Of Electronics Junk
The Great Internet Migratory Box of Electronic Junk

Finished 1
How to make a Sawed-off USB Key

AVR microcontroller projects

Using an ADXL330 accelerometer with an AVR microcontroller

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Kit Projects

AVR Target Boards

Four Panels 2
Interactive Table Kits

Resist1- Wall hanging

Peggy v 2.0

Crafty Projects

Q*bert close-up

vintage software book handbag
Software Handbag

iPod inside
iPod cozy

Earrings 2
Fimo Fractals

Miniature Art Car
Mini Art Cars

New wing
Umbrella Bat Costume v 2.0

Food Hacking

Cooking hotdogs

555 LED flasher 1
Circuitry Snacks

Googly FSM
Edible Googly Eyes

Sierpinski Cookies-11
Fractal Cookies


Sugar Chain
Printing complex shapes: Sugar Chain

Before and after 2
Candyfab improvements: higher resolution and edible output


Usage 3: First operand
Rotary Fraction Adding Machine

toner - 15
Electric Origami

Observations & silly projects:

Cat volume computation
Volume of a cat

Pacman Halloween

Lego Projects:

Lego Shooter
Forbidden Lego review & build

Technic Bits
Efficient Lego Storage


suction tool
Obscure electronics tools

Lee Valley & Veritas catalog
Lee Valley & Veritas Catalog Review


Twisted leads (close-up)
LED Stoplight

All the parts
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HP Color LaserJet 2600n

Sierpinski Cookies

Sierpinski Cookies-11

A few months ago we showed you how to make beautiful fractals in polymer clay.

Take that idea, run with it, and where do you end up? In the kitchen, making Sierpinski cookies! These cookies, made from contrasting colors of butter cookie dough, are a tasty realization of the Sierpinski carpet, producing lovely, edible fractals.
As with our earlier project involving clay, you can make these by using a simple iterative algorithmic process of stretching out the dough and folding it over onto itself in a specific pattern.
Continue reading Sierpinski Cookies

Iterative Algorithmic Plastic Sculpture: Fimo Fractals


Earrings 2

One of our favorite shapes is the Sierpinski triangle. In one sense, a mere mathematical abstraction, on the other, a pattern that naturally emerges in real life from several different simple algorithms. On paper, one can play the Chaos Game to generate the shape (or cheat and just use the java applet).

You can also generate a Sierpinski triangle in what is perhaps a more obvious way: by exploiting its fractal self-similarity.
Continue reading Iterative Algorithmic Plastic Sculpture: Fimo Fractals

Make your own 1952 Fraction-of-an-inch Adding Machine

Adding Machine in case

Last weekend we took a trip to Urban Ore in Berkeley, where I found an incredible gem: this “Fraction of an Inch Adding Machine.” It’s a simple to use device that lets you add any number of fractions– from 1/64 to 63/64– quickly, automatically, correctly, and without thinking about it.

As proudly proclaimed on the bezel itself, this calculator design is covered under patent Des. 169941, submitted in 1952, and granted a 14-year term in 1953. Forty years after the patent has expired, it’s painfully obsolescent, and yet remarkably charming. The design is so simple and so obvious in how it works, and yet… there’s something almost magical about it.

But enough talk. Want to play with one? Using our pdf pattern and some office supplies, you can make a working replica in 5-10 minutes and try it out yourself!

Usage 3: First operand

Continue reading Make your own 1952 Fraction-of-an-inch Adding Machine