{DIY} Robot Cake for the Birthday Boy!

My son is a leap baby and this year, his fourth birthday, is actually his first actual birthday. Kind of a big deal.

He’s been planning his “Robot Radio” Dance Party since last summer and when it came to the cake, his demands were quite specific (this is clearly my son). Yes he is only turning four. I hardly had to plan this party at all, he was so specific with his requests.

“The cake has to look like a real robot. The whole cake has to be the robot, not decorated with robots. It has to be standing up (not flat). It has to have robot arms and robot legs but they have to be cake inside too. We have to be able to eat his arms and legs. And it has to be chocolate inside!”

I wasn’t entirely sure I could pull it off. But now that I have, I’m going to share it with you. Believe it or not, it wasn’t that tough. It just required a lot of thinking and planning. Lucky for my son, I like a challenge.

First of all – the cake is covered with a rolled fondant. You can buy rolled fondant but it tastes awful and costs a fortune. So I made my own using this marshmallow fondant recipe (I used crisco not butter). I’ve made it twice now and it’s actually pretty fun to make. If you have kids, they will enjoy helping you knead this stuff and will want to make it all the time. It keeps in the fridge so I suggest making it a couple of nights before you’ll need it.

The night before the party I baked three sheet cakes (that’s three boxes worth of cake). I used boxed mix but I doctored it with instructions that I got from Angry Julie Monday. Basically you substitute 1 cup of buttermilk for however much water was called for and toss in an extra egg. This is how you make box mix taste like cake from scratch. It’s magic!

Before cutting up the cake into squares for stacking and constructing my robot, I  turned the sheet cakes out onto a board. I used a long serrated knife to slice off the rounded top, giving me a nice flat surface for stacking.

From the three sheet cakes I constructed two cubes, a large one for the body and a small one for the head. I actually drew a template for the bottom one, and figured out that it took two sheet cakes to “build” it – two squares from two sheet cakes to form four layers. But then I wanted it a little taller so I cut into the third one!

I made the head cube only two layers tall out of the remaining cake.

To construct the robot I frosted in between all the layers and stacked. Before frosting the outside I gave the cube a little “trim” with my serrated knife on all four sides evening everything up.Then I frosted the outside. No need to make it pretty – the frosting is just there as glue.

I did NOT stack the small cube on top of the big one yet…

Before stacking the cubes I rolled out my fondant to a giant thin circle. It’s sort of stretchy and bendy and a little unwieldy. If you dust it with corn starch and fold the ends up (like you are folding it in thirds) it’s easier to carry to the cake, center it, and let it drape down over the sides. You will need to gently smooth and stretch it over the cake. The frosting will make it stick. Be patient and gentle. Do not tug.

I then trimmed the fondant around the bottom of the cake (leaving a little extra to tuck under the cake).

Now that I had my two wrapped cubes it was time to stack. Instead of skewers I used plastic straws to secure the two layers together. They work rather well and are far less poky.

The wrapped cakes didn’t look so great until after we gave the robot a fresh coat of paint. I used a cake safe spray to make the robot silver. That part was super fun and worked miraculously to camouflage imperfections & improve the robot’s appearance.

I used more straws (the bendy kind, of course) to attach his robot arms (mini donuts) and legs. Then we gave him some personality

Frosting was the glue that we used for his peach gummy ring eyes and candy button details. I fastened on the Dots candy on the side of his head using a toothpick. Lastly we added some silver pipecleaner antennae with a couple more Dots.

I was really thrilled with how this guy came out. I couldn’t believe I made the “Bleeping!” thing.

Cake confessions:

  • I couldn’t get my fondant perfectly stretched over all four corners so I cheated. I pinched to seal the excess along two of the corners and trimmed with scissors. Then I ran a damp finger over the cut edge to smooth it.
  • I also didn’t have a totally smooth edge along the bottom, which is why I used extra fondant to create the seatbelt around the bottom of each layer.



  1. Dimsum22 says

    Hi, you have inspired me to make this. I have never made fondant or a tower cake like this so I am a little nervous. I am curious, how did you store the cake overnight? I would make mine the night before and then serve it at the party the next day probably around 2ish.

    Also, how did you cut and serve it? I was thinking if it was stacked that tall maybe I should add a cake board in between some layers.

    Lastly, how many people did this cake serve? Did you have enough fondant or did you double your recipe.

    Thanks for the inspiractional post and the information. If I didn’t read this, I would never attempt to do this style cake.

  2. Megan says

    It turned out so cute! Just wondering if you know the dimensions for your template that you did. Thank you so much!

  3. says

    I’m embarassed to admit that I kind of “winged” it. My cake pans are all 9 inches though – more or less. The cake was about 12 inches high!


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