Hidden Moving Cake Mount (Surprise Inside)

My Mom and Dad share consecutive Birthdays and this year it was my Dad's 50th so I had to do something special. They gifted me a 3D printer on my birthday so I decided to make use of it to make their birthday cake a little more special. I designed and 3D printed this completely original design and integrated it with a 2 tier cake baked by my freind to give them a surprise when they cut their cake. There are multiple motions in this mechanism and I have added a video too so that you can have a look at the final product. Hope you like it! :)

PS. Video added at the end

1. Any CAD Software
2. 3D Printer + PLA/ABS Filament ( If you do not have a 3D printer, no worries. A similar functional mount can be made using Cardboard/Lego bricks. )
3. Hot glue gun / quick-drying glue
4. Thick Base Plate of any material for resting the cake and thin base for the upper tier.
5. Some tiny Bevel gears and shafts (Optional Based on design- discussed ahead) (I have used Lego pieces)
6. A motor and battery (I have used a Lego motor)
7. A Baker Friend who is ready to struggle and help you out with this XD.
8. A custom cake baked by this Baker Friend
9. Small Pieces of ribbon

Firstly, let us look at one of the core components of the mechanism. This surprise moving cake mount has a cake inside which rises from the bottom for which we have used the lead screw mechanism, This is also found in a lot of 3D printer Z axes. Basically, if you hold the nut and stop it from rotating and rotate the screw instead, the nut will move up or down. This same concept has been used by us to lift the cake up and down all while rotating the lead screw.

Now that we have decided to make such a complex project, we need to make rough sketches and then start with accurately dimensioned CAD models. You can use and CAD software like Fusion360/TinkerCAD/Solidworks/etc.

You should talk to your baker friend and discuss the final dimensions of the cake based on which you can model the mechanism inside the cake.

PS. Sorry for those messy sketches. I did get a scolding from my baker friend for this too hehehe.

In this step, we convert all our CAD files into .STL files and send them to any slicer software. The slicer software converts the files into a g-code file which is used by 3D printers and CNC machines as an input language. Here, I have used Cura Slicer which is a free-to-use software.

I have added a lot of STL files for your reference. Some of them are just tolerance test files and sample prints.

Now we 3D print all the parts one by one. I've used white PLA for this. The printer specifications/settings and the material are totally up to you.

Now we take the Thick Base and stick the lower mounts of the structure to it. Then we add the gearbox (bevel gear assembly) and shafts and then glue the upper mount as well. The Cake that moves up and down via the leadscrew will rest here.

Now we let our Baker friend do the magic and add the tasty tasty cake and ganache... yum! It's actually Belgian Chocolate filling with chocolate and vanilla sponge cake. After this step, the first tier is added.

Now once the base/lower tier of the cake is added and the finishing is done, we add the upper rail structure.

This structure does two things:

1. Provides support and constricts the moving cake while going up and down.
2. Becomes the base for sliding the upper cake/upper tier on both sides.

Here, we add the two halves of the sliding cakes onto the upper sliding pieces mounted on the rail. Before gluing the plate of the cake to the sliding pieces, we add a ribbon in between which will help us in pulling and sliding the cake halves to the sides, thus making space for the central cake to move up.

Finally, we add the lead screw and the central cake base with the cake after threading the cake base into the lead screw.

Note that the lead screw will have a + shaped slot in the bottom for something like a Lego shaft to help it rotate.

Also, the central moving cake will be hollow in between due to the space required for the lead screw.

Assitance of your baker friend is highly essential in this step as well as the previous steps. XD

Finally, we let our baker friend close the cake and add all the finishing touches and beautifications like flowers. (White roses in our case) We also test the mechanical assembly before this and then bring the cake home carefully. . Fingers Crossed!

Here is the final video of the cake before the cake cutting.(MAKE SURE TO WATCH THE VIDEO :) ) This was a huge surprise for my Mom & Dad and they really loved it. I'm glad I was able to pull this off (with the help of my baker friend of course!) GGs.

So basically, the upper layers are slid out using the ribbons and then using the motor, the lead screw rotates which brings the central cake upwards. Surprise Surprise.

Hehehe.

I hope you'll like this and this inspires you to make something like this for your own loved ones. Thanks for being a small part of this journey. Do let me know if you need some ideas or help making something like this of your own.