I recently acquired a 3D printer. It's a great tool. Alongside learning about the printer, it's allowed me to learn 3D design and the additive manufacturing process.

The part is available to download on Printables if anyone wants a copy: https://www.printables.com/model/809592-breville-vst041-sandwich-maker-base-plate

As you can see in the photos, the base of my sandwich maker is damaged. One corner is missing, and the remaining part has a big crack. This problem prevents the device from sitting level on the work surface, causing molten cheese and other greasy fillings to run down the back of the machine onto the surface.

Let's remove the damaged part for measurements. There were five screws, one hidden under the label.

I used a combination of rulers and digital callipers to take the measurements. For the broken parts of a symmetrical object, you can measure to the centre and mirror the features down the centreline.

I made sure to measure the width, length, height and thickness. I did this for both sides of the part and the internal fitting part on the toaster itself. For the screw holes, I measured the pitch (the distance between the centre of two holes) and the centre of the holes towards the edge of the part. To calculate the curved corners, use maths... or as I did, square the part off and then measure the distance from the corner to the midpoint of the curve, and then input that distance into your modelling software and let the computer do the calculations.

Now that I have the measurements, it's time to fire up Fusion 360 and input our parameters. Creating a parameterised design allows you to make quick alterations during the test and iteration phases.

Once the parameters have been input, we can then sketch the part. I sketched the outer side of the part first and then the inner. I used the outer sketch to constrain the measurements for the inner side of the part. This way fitment protrusions and screw mount points will adapt to the size of the outer area when making any modifications during the testing.

After drawing all the required parts on the sketch, I extruded each bit to create the 3D model using the parameters set earlier. Again, this will help when making any modifications during testing.

Now that I had the design, it was time to start printing test pieces. To minimise filament waste, I usually do not print the entire model when testing. I prefer to print 2-3 layers and check if the part fits. After testing the fitting, you can return to the 3D design and make any alterations. Then reprint a test piece.

I went through two design iterations to find the perfect fit and alignment. Additionally, my first final print was a misprint with a z-axis layer shift towards the end. You can see this in the photo, a line or crack down the left side. I had to reprint the final piece.

I printed the final part at a 45° angle. Printing like this removes the need for large amounts of support material and increases the strength by creating a slight offset of each layer overlapping and interlocking the one below. Think of this similar to building a brick wall.

The final piece fits well, has solved my problem, prevented unnecessary e-waste, saved me £45, and taught me many new skills.

I used PLA+ filament. While generally not the best choice for this type of part, PETG would be recommended (higher flexibility and temperature resistance) - it was all I had. This part of the sandwich maker doesn't exceed the 62°C glass transition temperature (thermal deformation) of the filament I used, so shouldn't pose a problem.

I took the opportunity to clean the device before fitting the new part. After years of use, you never realize how much crud can seep through the cracks into areas you don't usually get to see.