Tartan Cake (and 3D printing)

Posted on Sep 30, 2016

My girlfriend works for a company that was having a cake making contest recently. This company has its own registered tartan (yes, individual tartan patterns can be registered) and a logo of an eagle which looks pretty cool and we figured would look even better all made out of icing.

The cake

A quick google for “tartan icing” reveals minimal decent results and what is there is mostly just printed patterns rather than hand-made. There wasn’t much in the way of eagle cutter shapes in the baking section at Tesco either so we had to come up with our own plan and, as is getting much more common with me, get some parts 3D printed by Shapeways.

The first step for me was the eagle logo icing cutter. I initially looked online for a vector image of the company logo but came up with nothing, so the next step was to look online for the highest resolution raster format logo I could find and trace it in Adobe Illustrator (I actually asked someone I work with to do the Illustrator bit as I didn’t have it installed myself).

I then imported the vectorised logo into FreeCAD and extruded the individual paths to different heights to make a 3D representation of the icing I wanted to end up with. I raised the border outline 3mm and the wings and body 5mm. For finer detail like the eye and feather marks around the neck I indented them from the wing and body by just 1mm to leave a slight impression.

Icing cutter negative

I started having some issues with FreeCAD so for the actual cutter I swapped over to Blender as I’m more familiar with it, importing the negative made in FreeCAD and working from there.

I started by copying and expanding the base outline so that I’d have a sturdy 2mm cutting edge around the perimeter. I then extruded that shape up about 7mm to give me a 2mm thick top plate on top of the 5mm tall wings / body. After a little thought about how the icing would form in this icing cutter / mould I made a couple of duplicates with some holes in the top plate to allow air in and stop the icing being suctioned onto the cutter / mould. I then used the boolean difference modifier in Blender with this new shape and the negative to get the cutter model I needed.

Icing cutter variants

When I uploaded these models to Shapeways and requested prints I got an email back letting me know the fine detail of the eye and nostril of the eagle, as well as some of the finer feather-point detailing, might not work given the detail resolution of their printing method. As we didn’t really care too much on the sub-millimetre accuracy of the print I had the chance to take part in Shapeways “Print it Anyway Pilot”.

Icing cutter prints Shapeways letter Icing cutter detail

We received the prints and the detail was perfect for what we needed. Shapeways had included a nice little note with the package thanking us for giving the pilot scheme a go and we were very happy with the results.

We rolled out some yellow icing and gave the cutters a test. After a few failed attempts with the icing getting stuck, despite the air holes on some of the cutters, we eventually started getting reliable results after rolling it to a certain thickness and generously coating the mould / cutter with icing sugar before cutting.

Icing cutter test

With the eagle logo sorted the next challenge was the tartan icing. I measured out some tartan fabric of theirs with a ruler first to get the individual colour “block” sizes and wrote down the details for a single “tartan block” which would repeat. I then put it all into a Google sheet, summed up the sizes by colour and printed a plan.

Working on the tartan icing

What followed was hours, literally hours, of carefully rolling out, measuring, cutting and collecting of all the icing blocks.

140 icing rectangles were needed

6 unique colours

9 unique sizes

Hours of effort

As you can see in the photo above we cut all the blocks first and then followed the printed and highlighted plan at the bottom to lay them out on a black piece of backing icing.

Thankfully the end result was actually pretty decent.

Tartan icing result

The tartan icing sheet then went on top of the main cake, got trimmed and taken to work the next day for judging.

The final cake completed

Thankfully after all the effort the cake won the contest!

All that was left to do was clean up the mess that was left in the kitchen after making the cake the night before…

Kitchen mess