# You're reading: Posts Tagged: baking

### Geogebra to Cake in Five Steps

In the Aperiodical’s Big Internet Math-Off 2019, Becky Warren posted an entry about Geogebra’s ‘reflect object in circle’ tool (it’s the second article in the post). I enjoyed playing with the tool and, after making a few colourful designs, it occurred to me that one of them would make a great cake for the MathsJam bake-off. It would only work if the curves were accurate; sadly this would be beyond my drawing abilities, and definitely beyond my piping abilities. But with some help from 3D printing I thought I might be able to manage it.

Here are the steps I used to transfer the design to a cake.

## Step 1 (Geogebra) – Save as an image

I started by simplifying the design. Squares are straightforward, so I only needed the part within the centre circle. I hid all the squares and removed all the colours, then thickened the lines to make them easier to see. Finally, I took a screenshot and saved it as a bitmap image.

## Step 2 (Inkscape) – Convert image to path and generate scad

The next step was to use Inkscape to convert the image into an OpenSCAD file that can be used for 3D printing. If you google ‘Inkscape OpenSCAD’ you’ll find several extensions that will do this; I used Paths2OpenSCAD.

To generate the scad, start by importing the image into Inkscape. Then, with the image selected, go to Path > Trace Bitmap. This opens up a window with lots of options; accept the default and click OK, then close the window. Inkscape has now converted the image into a vector path; this means that it has coordinates for each point on the path.

Now go to Extensions > Generate from Path > Paths to OpenSCAD. This opens up another window. In the output file box, enter the location to save the scad file, then click OK. Now you can open the file in OpenSCAD.

## Step 3 (OpenSCAD) – Scale design

The generated OpenSCAD file starts like this.

It has a method called ‘poly_path854’ (a new number is generated for each file). This method uses the coordinates of the points on the path from Inkscape to make a polygon in OpenSCAD.

Pressing F5 to preview shows a replica of the image, rendered as a 3D model.

At the very end of the file is a line that calls the ‘poly_path854’ method, passing in a number. The number is the height of the object when printed – you can change this to suit your needs.

The part that I found difficult was to work out the size the model would be when it was printed. The axes on the OpenSCAD preview window give some indication, but it’s not possible to read accurate values from it. I wanted my model sized appropriately to match a square cutter that I already owned. In the end, I printed out a 1 mm high model so that I could measure the original size without wasting too much plastic, then I scaled the entire model to match the square cutter. The final line of the file became

scale([6/(4.2*sqrt(2)),6/(4.2*sqrt(2)),1]){
poly_path854(5);
}

## Step 4 – Print

I sent the model to the printer, and a few hours later I had my cutter!

## Step 5 – Imprint on cake

Once I had baked the cake and covered it in fondant, I used the cutter to make an imprint of the design on the icing.

Now it only remained to cut the squares around the edges and give it some colour. I used a small amount of vodka to thin out paste food colouring so that I could paint on the fondant icing. (Honestly, it was a tiny amount of vodka – less than 5 ml over the entire cake.)

That’s it! Geogebra to cake in five steps. Here’s the finished cake, alongside the original design in Geogebra.

### Baking Babylonian cuneiform tablets in gingerbread

The MathsJam conference has a baking competition. My friend the archaeologist Stephen O’Brien tweeted a while ago a link to a fun blog post ‘Edible Archaeology: Gingerbread Cuneiform Tablets‘. Babylonian tablets are among the earliest written evidence of mathematics that we have, and were produced by pressing a stylus into wet clay.

So it was that I realised I could enter some Babylonian-style tablets made from gingerbread.

I made a gingerbread reconstruction of a particular tablet, YBC 7289, which Bill Casselman calls “one of the very oldest mathematical diagrams extant“. Bill writes about the notation on the tablet and explains how it shows an approximation for the square root of two. I’m sure I didn’t copy the notation well, because I am just copying marks rather than understanding what I’m writing. I also tried to copy the lines and damage to the tablet. Anyway, here is my effort:

In addition, I used the rest of the dough to make some cuneiform biscuits. I tried to copy characters from Plimpton 322, a Babylonian tablet thought to contain a list of Pythagorean triples. Again, Bill Casselman has some interesting information on Plimpton 322.

Below, I try to give a description of my method.

### The competition I entered into the first MathsJam Competition Competition

A couple of weekends ago was the big MathsJam gathering (I might call it a recreational maths conference, but this is discouraged). Two of the delightful sideshows, alongside an excellent series of talks, were the competitions. The Baking Competition is fairly straightforward, with prizes for “best flavour, best presentation, and best maths”:

The first will reward a well-made, delicious item; the second will reward the item which has been decorated the most beautifully and looks most like what it’s supposed to be; and the third will reward the most ingenious mathematical theming.

You can view the entries from this year on the MathsJam website.

### Review: Cakes, Custard and Category Theory by Eugenia Cheng

We’ve often mentioned category theorist and occasional media-equation-provider Eugenia Cheng on the site, and she’s now produced a book, Cakes, Custard and Category Theory, which we thought we’d review. In a stupid way.

### How I Wish I Could Celebrate Pi

People with an interest in date coincidences are probably already getting themselves slightly over-excited about the fact that this month will include what can only be described as Ultimate π Day. That is, on 14th March 2015, written under certain circumstances by some people as 3/14/15, we’ll be celebrating the closest that the date can conceivably get to the exact value of π (in that format).

Of course, sensible people would take this as an excuse to have a party, so here’s my top $\tau$ recommendations for having a π party on π day.