I wanted to make a case to carry Goldfish crackers that was fun and practical. I have been 3D printing for a few months and have had a lot of fun downloading designs made by others and learning the ins/outs of 3D printing. As with many 3D printer novices, Tinkercad has been my main tool for designing some of my own models. As I’ve become more proficient with

Tinkercad, I have also been trying to design more complex pieces using Fusion 360, a professional design tool available to hobbyists for free.

Supplies

The only item I had to purchase was the 6x2mm neodymium magnets. They are available on Amazon and are inexpensive. They are usually sold in quantities of 100 so keep those creative ideas flowing. The pack I purchased is no longer available so a simple search for small neodymium magnets should get you what you are looking for. Be sure to select the right size.

• 100 PCS Mini Magnets, 6x2mm Small Magnets

• Super glue

Step 1: Download

To get the initial shape for my case right, I took a photo of an actual Goldfish cracker and using the Insert Canvas function in Fusion 360 imported the photo. Then using the Fit Point Spline tool, I traced by hand the outline of the Goldfish cracker.

This is the starting point for creating your designs in Fusion 360. You create your initial sketch and then you can add dimensional shape to your sketch. In this case I wanted my case to be 32mm tall and for the walls of the case to be 2mm thick. Using Fusion 360’s extrusion tool and shell function I was able to create the shape I wanted.

With this sketch complete, it was time to move onto the lid. The lid was more challenging because I had to design a hinge mechanism so that the case could be easily opened and closed. I also decided that to secure the lid, I would use small neodymium magnets. This would make it easy to open while also ensuring it closed securely, keeping those precious crackers safe from spilling out.

I used my earlier case design as a template to ensure an exact replica would be made for the lid. Of course, it must be the reverse pattern to match perfectly since this was hand drawn. Using Fusion 360, I imported the original case I made earlier and rotated it 180 degrees to get the mirror image of the case. I do not have a great deal of experience with Fusion 360 so there are probably faster and easier ways to do things, but I made it work (after watching some Youtube videos of real experts).

Now that I had the lid case mirrored, I needed a hinge which means I had to split the lid and add hinge pins with corresponding indentations to hold the lid in place. Fusion 360 has a neat tool that lets you split your design along any line you choose. The Split Body tool was simple enough to figure out how to use. I chose a spot near where I thought the tail section should end and voilà. Next, I needed the hinge. This was accomplished by adding a cylinder with a hole designed into the piece and attached to the tail section. Then a corresponding cutout on the head piece with matching tabs that will fit into the holes in the cylinder. A simple hinge design that requires no additional parts.

I also added a spot on the nose to hold one magnet. These are the small, 6x2mm neodymium magnets you can get on Amazon.

Of course, I now needed to go back to my original case design and add in the corresponding holder for the opposite magnet. Using a little super glue to hold the magnets in place is all that is needed. Just make sure to orient the magnets so they are attracted to each other. I also added little tabs to the back of the case to make alignment easier when gluing the pieces together.

Next is the famous smile and eyeball. Using Fusion 360’s Fit Spline tool again, I simply freehanded a small piece for the smile and added a small half-sphere for the eye.

Step 2: Print

It’s now time for printing. I used Inland PLA+ yellow for the case and some Inland PLA black for the smile and eyeball.

Step 3: Assembly

Once all the pieces are printed it’s time for assembly. The first step will be to assemble the lid. This is the trickiest part because basically, you must force the pieces together with a slight twisting motion. I used PLA+ 3D printer filament because I understood it to be more durable than regular PLA. Don’t be afraid to “click” it into place. I was able to do this without damaging the pieces and once in place it should move freely.

With this step completed, I inserted the magnets with a little super glue to hold them permanently in place. REMEMBER to insert the magnets so they attract each other. You want to make sure you do this right because if you get it wrong, the super glue will ensure you need to reprint the pieces.

Next, it is time to attach the tail section of the lid to the body. Place a small amount of super glue only on the tail section of the lid. You get one shot at this so that is why I added the alignment tabs on the body. Once the glue has been applied, align the tail section above the body, using the tabs to keep things aligned and press the pieces together. Super glue is great but very unforgiving so take your time and make sure the alignment is right before pressing the pieces together.

All that is left is to add the eyeball and smile. I used a pencil to mark where I wanted these placed. Put a little super glue on the piece and set it in place. Again, you get one shot with super glue so test and mark where you want the pieces before getting the glue out.