Convert an Image Into a Custom Cookie Cutter

Hi, and thank you for reading my Instructable. I am going to show you how you can take any image and using free software turn it into a 3D design to be 3D printed. Don't have a 3D printer? Check your local library! I just recently found out that my local library has a Maker Space complete with laser cutters, large format vinyl printer and two 3D printers. All can be reserved through the website, and used for just the cost of materials. The Link one cost me $0.90 and Zelda is larger so she was $1.45. Read on to find out how you can turn your image into a cookie cutter (and then into cookies)!

Supplies

For this project I will be using 3 different pieces of free software.

Gimp
Inkscape
Tinkercad

I also used Google Image search to source my initial images.

Step 1: Find Your Image

I wanted to make Legend of Zelda cookies for Santa this year! Off to Google Image search to find some Zelda related images.

Note: I will be referring to the backgrounds of the images as either "simple" or "busy". A simple background is one that is a solid color or transparent. Usually "transparent" is indicated by a gray checkerboard background. Basically, it doesn't have anything "going on" in the background, and is easy to cut around. The first image is an example of a simple image.

In contrast, a "busy" background is one that has other images, patterns, or landscapes. Or, there are lots of little areas to cut around, such as Zelda's hair, in the second image.

When selecting an image, I suggest you first start with an image that has a simple background (like Link). This will make your work in Gimp much simpler. For most of this Instructable, I will use the image of Link on a yellow background (Image source: https://www.polygon.com/23392291/zelda-link-to-the-past-pajamas ).

Once you have found your image, download it, and open it up in Gimp (https://www.gimp.org/).

Skip step two if your image fits the description of "simple".

Continue to step two if your image is "busy" (like Zelda's image).

Step 2: Remove the Background With Gimp

(skip this if your image is "simple")

This is a more advanced step where we will be manually removing the busy background so we can get a good selection on just the image we want.

Note: I am using a "busy" image of Zelda here to demonstrate. Image source: https://www.zelda.com/breath-of-the-wild/assets/media/wallpapers/desktop-4.jpg . The image of Link is "simple", so I didn't need to do this part.

For this process we are going to be using a couple different tools within Gimp to remove most of the background and leaving just the image we want to make into a cookie cutter (in this case, Zelda).
First, we are going to use the "Free Select Tool"(it's the button that looks like a lasso, yeehaw!) This lets you make a free form selection.
We are going to use this to remove a chunk of the background by drawing a line with the selection tool around Zelda.
It doesn't have to be perfect, just go a little bit outside the lines and get the general shape without cutting into the image you want to keep.
You will move all the way around the image and connect it back to the starting point.
Now let's delete all the stuff we don't want. Go to the top menu and select Select -> Invert. Now the part you didn't select is selected.
Hit delete to remove this part of the background.
Now to cut the overall image size down go to the top menu and select Image -> Crop to Content
To "deselect" the white part, go to the top menu and select Select -> None.
If you like details, you'll love this part! We are going to zoom in and delete the rest of the background. This doesn't have to be exactly precise down to the pixel, but you do want to get pretty close. In some cases, I ended up going a little inside the line and sometimes I left it a little outside the line. Again, it's not perfect, but close. Anything not perfect can be cleaned up in Inkscape, as you'll see later.
Tips for erasing
Use a hard line for your eraser, this way you don't have real fuzzy edges.
Play with the size of the eraser. In most sections a larger eraser will save you time and do the job.
Also adjust your brush shape. Round works nice for tight spots, rectangle is good for larger areas.
Zelda's hair was a problem for me. It is very intricate at the ends. I actually ended up erasing to a more simple design, knowing that in the end it just needs to look right overall.
Zoom in and out as you go. Get a feeling for the overall image and adjust as you need to.
Once you are comfortable with how it looks, save a copy and move onto the next step.

Step 3: Select and Export the Path

We have an image now with a background that is easy to work with. Using Gimp we are going to create a path from our image.

First we will use the Fuzzy Select Tool (it's a magic wand). Click on the Fuzzy Select Tool.
With the Fuzzy Select Tool selected, click anywhere on the background outside of the image you want. It should now have the background selected. If it has not selected all of the background (for example if you have a background portion on the other side of your image), hold shift and click on the other background areas until all are selected.
We have the background selected, but we want to have the image selected so we will invert our selection. In the menu at the top of the screen, select SELECT -> Invert. This will invert your selected area so that the image we want is now selected.
Next we are going to turn your selection into a Path. To do this again go to the top menu and select SELECT -> ToPath
You should now have a Selection saved in the Paths tab (see pictures for this location, it can be tricky to find). Right click on the Selection and in the menu that appears select Export Path.
Save your path as myAwesomeCookieCutter.svg (or something clever).
You can close out of Gimp. It will likely ask if you want to save your work.

Step 4: Clean the Path in Inkscape

Now we are going to open up our path with Inkscape. If you have a super clean image this step might be pretty quick and easy. In my case, it was not. Let's carefully walk our way around the path and clean things up with Inkscape.

Inkscape can be downloaded from here: https://inkscape.org/

I found this process to be a lot of guess and check work. Undo is going to be your friend as you work. You can use CTRL+z to undo, use Undo from the edit menu or use the undo arrow on the right menu.

Open your myAwesomeCookieCutter.svg file you saved out of Gimp in Inkscape.
Select the paths button from the menu on the left side of the screen (it is near the top)
Click on the line that outlines your image to open up the path.
First we are going to try and let Inkscape simplify the path for us. Go to Path -> Simplify and see how the tool does. It should reduce the number of points in the path. If you do not like the results, just undo them.
Now, let's start in at any point along the path. There is a Z in the lower right hand of the screen for Zoom. Click the + to zoom in.
In my example image you will see a lot of points that are not even on the path. The first task is to delete all of these. Click on the points and hit the delete key. You can also use your mouse, click and drag to select multiple points at once. Remember if at any point you delete too much and the path get wonky, just undo.
Continue making your way around until you have cleaned up all the extra off path items.
Now, zoom out a little bit (hit the - next to the Z in the lower right hand of the screen) and take a look. Does the path look clean. Are the curved lines smooth, straight lines straight? If not, continue ahead. If it looks right, sweet! You can save and move on.
If the path is not perfect, we are going to need to clean it up a bit. This part is a bit of trial and error. Be patient, remember anything you do, you can undo. Try the steps below and see how it looks.
First thing to try is to delete extra points on the path. Zoom back in and walk the path. If you see a cluster with a bunch of points right next to each other, delete a few of them. Typically, removing extra points in the path will cause it to smooth out a bit. Each point in the path should represent a change in direction or be used to adjust a curve. Typically less is more here.
After removing unnecessary points, you can now start to play with the path between points. When you click on a point you will see two lines coming out of it, with a circle on the end of each. Grab that circle with your mouse and move it about a bit. This is going to control how the path looks between the two points. Both points have these lines to play with each to see if you can't get that portion looking cleaner. Try something, undo, adjust, adjust, undo, try again, zoom in, zoom out, love it, move on.
Sometimes you mayb find that to get it right you need to add a point between two paths. To add a point, select the first point on the path, hold shift and then select the second point that you want the new point to come between. Both should now be highlighted blue. Head up to the top toolbar and select the add a point button.
Once everything looks good, go ahead and save out a copy of your cleaned up image and close Inkscape.

Step 5: Create the 3D Design in Tinkercad

Let's now move onto Tinkercad.

Tinkercad can be found here: https://www.tinkercad.com/

In Tinkercard we are going to click on the New + button and select 3D Design.

Now in the 3D design view we are going to Click on the Import Button.
Select file you just created in Inkscape.
Next it is going to ask you how large you would like your imported image to be. For most cookie cutters you will want to go with around 100mm in length. This is a nice sized cookie cutter and is roughly the size of most the store bought cookie cutters in my kitchen.
Click Import to import the image.
Once imported you will notice it comes in as the full image and does not look like a cookie cutter. To fix this click on the imported image so we can adjust some settings.
This first image is going to be the top of the cookie cutter which is flared out to make it easier to handle. In the menu that appears use these settings:
Fill Mode: Outer Line (You have to set this first before the other options)
Height: 2 (mm)
Quality: 11
Corners: Sharp
Line Width: 5 (mm)
Optional: Set the color (Light Green for Link)
Now we are going to repeat this process but this time we are going to be building the walls. Click the Import Button
Select the same image
Set it to the same size (100mm in length for those following along at home)
Click Import to import the image.
Again we have the full image so let's adjust the settings. Click on the newly imported image and use these settings.
Fill Mode: Outer Line
Height: 15 (mm) this will make the walls 13mm tall.
Quality: Turn it up to 11
Corners: Sharp
Line Width: 1.25 (mm)
Optional: Set the color (Dark Green for a little contrast)
Next let's group our two pieces together. Hold the shift key and click on the two pieces.
Use the Grouping button to group the two pieces together.
Because we are printing the top of the cookie cutter on the bottom we need to mirror our image. With the group selected click on the Mirror button and then click on the bottom set of arrows.
Finally give your project a name.

Step 6: 3D Printing Details

As I mentioned in the introduction, I do not own a 3D printer. I use the ones available at my local library. As such, I do not have a lot of advice about the settings to use for printing. I am sure some kind person in the comments can help out or if you are like me and using a shared space, there is likely someone there who can help out.

That said, both cookie cutters were printed on a Cura Ultimaker 2+. I used a brim setting and only on the outside so the inner portion of the cookie cutter would remain open. The rest of the settings I left set to the defaults.

I exported my design from Tinkercad and took it to the library to be printed.

Step 7: Cookies!

Here is our end result..the cookies. I am super proud of how this one turned out and the cookies look great. I was really nervous that would spread too much in the oven but they came out looking great. I had my wife help with frosting the link for the title shot, I give it a shot with Zelda and then we let the kids help with the other Link cookies. I think they turned out great and were a ton of fun to make.

I can only image how these cookies would have turned out in the hands of someone who knows how to do some amazing frosting work...hint hint wink wink, I would love to see some cookie pictures in the comments.

Thank you for reading my Instructable. Hopefully it has inspired you to give it a shot. Even if it hasn't, hopefully it has at least given you a craving for some cookies.