CinnaBrooch consists of a homemade mechanical leaf shutter, a cinnamon bun, and a moisture sensor. The moisture sensor rests inside the armpit. When you are nervous and perspiring, the shutter will begin to open and close. The alluring aroma of cinnamon buns will then waft over all in your vicinity.

Tutorial in progress! Finishing it over the next few days. Feel free to check out what I have so far:

Difficulty level: Intermediate/ Easy

(The electronics are pretty simple! The structure is the hard part here, access to hand tools is a must)

1. Design

I should probably make this the first step of all my tutorials! It’s rare to have an idea, draw out a design, and achieve it the first time. I don’t always document the failures well. But happen to have pictures of this one. This first version of the Cinnabrooch, I thought I could poke holes in an enclosure and spin a fan around to waft the cinnamon smell out. (left two pics).

While that design did allow for a gloriously massive cinnamon bun, it didn’t really do a good job wafting the odor out. I realized I needed a much bigger hole to let the air out and then I needed that much bigger hole to open and close, and so that’s why I ended up making something more like a mechanical leaf shutter.

Your design will no doubt change as you start working, but it’s always good to think about where you want it to go on your body, how you’re going to package everything, and how you want it to look in the end. I used clear acrylic for the shutter, so you can always see the bun, at the decision dictated a lot of my other decisions.

2. Make the Structure

Some of my projects are more challenging on the electronics end, that’s not the case for this one. Electronics are pretty straightforward, it’s the structure that’s tricky here.

First of all, this is the tutorial I followed to make my version of the leaf shutter, I had to modify it somewhat to make it work with the acrylic and of course had to automate it. But I think their shutter is much prettier than mine!! And more functional, because they used a flatter material, the metal.

So my decision to use acrylic is what made my shutter a little more difficult to pull-off, because it’s a material that is not as thin as sheet metal. But like I said, I really wanted to it to be clear, so I got some 1/16 inch clear acrylic, and I laser cut it out using the file shared by Kommodore on Instructables. (Cutting the sheet metal by hand is easy, but acrylic is harder, would need a steady hand and a scroll saw, and I had neither at that time so I used a laser cutter.)

But what I found right off the bat was that since my material was thicker, it wasn’t going be able to lay flat, and therefore I needed different sized pins. Here’s what I mean:

The little “leaves” need to pass over the top of each other for this whole thing to open and close. The acrylic leaves are too thick, so I had to kind of stack them up. So instead of using the pins from bike chain suggested by Kommodore (which is a great idea) I cut down descending pieces from a steel rod on a chop saw.


Tried to get two versions of each size, but wasn’t as precise as I should have been.


I thought I might be able to laser cut a couple pieces of the base plate design and stack them but it was not deep enough to hold the lower pins (since my pins were getting so long). I think wood would have worked best, but I didn’t have access to a table saw or router at that time (recurring theme in this one, had just moved and did not have access to usual tool when I was trying to do this project!) so I found that foam worked pretty well:

The foam slots are basically keeping my rods on a track. The steel rods are increasing in size, because the leaves that are on top are also higher, and therefore further from the base. (This is not an issue if using a thinner material).


So the piece that will be on the bottom needs the shortest peg on the bottom side, and the longest peg on top side, because that would be the furtherest from the top piece. A little confusing, but I laid out my pieces one by one and super glued the rods in:

smallest / biggest
2nd smallest / 2nd biggest
and so on. Somewhere in the middle the rods were the same on both sides:
medium/ medium
and then it flipped and the last few pieces were:
2nd biggest / 2nd smallest
biggest /smallest

Example of biggest/ smallest:


I actually just did one side on all of them first to make it easier to see:


So that top most piece needs a rod pointing up, to be able to grab the top piece that we will add later. And since it is close to the top already, it will get a short rod.


Here it is before I switched to a foam base.

The top piece is a little hard to see on mine, because of my decision to use clear acrylic. but it is a disk with holes in it that keeps the top pins in place. IMG_1718

This is Kommodore’s top piece, in white:


See how the pegs poke through it? Mine are doing the same thing but harder to see. And since the whole thing is deeper we also have some longer pegs.

You should be able to twist the top piece by hand to test your shutter at this point. One benefit to using foam as the base was that it was easy to make changes. Some of the longer pieces were dragging a little so I cut out the ridges deeper with a knife for those ones.

2.2 Structure Housing 

As you know by now, this was a mostly shop-free project. (Aside from the laser cutter and chop saw, which I was lucky to get access to). So I had a reel of RGB LEDS (from The Perfect Fit!) and I cut out the inside of that with combo of a knife and wire cutters, to get a nice rigid  plastic circle.

I then cut out the same shape in cardboard and glued the plastic to that. Then I cut a long strip of cardboard and scored it vertically so that it could bend, and I bent that around the circle frame to make a wall and glued it into place. It’s pretty sturdy! I think it was an Amazon prime box 🙂

So that’s my top piece to cover my Cinnabrooch structure.

Then I cut out my base piece, which has the circle shape of my top piece, but with an additional side piece to leave space for my motor, since I am going to motorize this guy. The shape ended up changing somewhat, as you’ll see, but this was the first layout.

Once in this phase you definitely have to jump between the electronics portion and the structure portion, because you have to know what you’re using and make sure it fits. I knew I was using a standard tower pro servo motor (not a micro) because it takes a decent amount of force to spin this thing.

So if you looked at the Instructable tutorial (which you should because it’s great) you’ll notice the creator opens and closes the shutter by rotating the top piece. that was my original plan too, but then I switched to controlling it from the bottom because it was more stable and easier to hide.

(next part coming soon).

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