HWK F2: CAD - Designing a Valentine's Day Gift

The CAD software I chose for this assignment is Fusion 360 because the virtual machine kept crashing when I tried to render organic shapes (irregular, high density objects), so I decided not to tortue myself and try out new features that I never used in Fusion 360.

I am not experienced with Fusion 360, but it is far greater than with Solidworks. I only worked with basic shapes like cylinders, boxes, or cones to design tools for my research at a lab, so in order to design a bunny, I have to learn how to create and work with complex shapes.

To guide my design process, I outlined following design requirements:

• Has to look like a bunny with a Valentine related item.
• Minimal amount of printing support to improve surface quality.
• Printing time below 5 hours for one bunny.
• Main body height should not exceed 8cm.
• Bunny has to balance itself on its foot and tail.
• Detail resolution after printing up to 1 mm.

Since this is my first time working with complex shapes, I avoided setting strict dimensions and harsh design requirements to make the learning experience more enjoyable and leave some room for creativity. Also, I am neither an artist nor sculptor, so expecting a real-looking bunny to be made using Fusion 360 would be an overkill for me.

1. Creating the main body

Challenge: the main body of the bunny is irregular and the design has to account for the head to smoothly fit afterwards.

Solution: use loft tool to connect multiple 2D sketches into an approximated 3D shape.

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Step 1. Creating the side view 2D outline. 

I used sketch tools to sketch a close-enough side view outline of the body. I could have used the image and try to outline as accurately as possible, but since I wanted to spend more time on other parts of the design, I did this part quickly by approximating the shape.

Step 2: Creating horizontal outlines

Since I want to use the loft tool to generate shapes of interest, I have to create as many horizontal outlines at different z-levels as necessary for the best approximation of the side view outline.

Note: the side view outline is used purely for reference to create horizontal outlines at different height levels.

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Step 3: Using loft tool to create 3D body.

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When I selected the loft tool, I had to select all horizontal sketches to generate a 3D shape. However, the loft tool kept failing when I tried to run it after selecting all sketches. I realized that I was not selecting the sketches in the right order. I was supposed to select them one by one from top down or bottom up to guide the shape, so it didn’t work when I selected the sketches in the random order.

And voilà, it worked!

Lesson 1: select sketches one by one in consecutive order to guide the shape. 

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2. Making bunny’s head

Okay, we have mastered the creation of complex shapes. Now we will repeat the same process to create bunny’s head.

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The bunny is technically done! The anatomically concerning arching back will be dealt later using the fillet feature. Now we have to add some minor details to make it more obvious that this is a bunny.

3. Bunny ears (or else it would become a frog)

I did not look forward to making bunny ears as it seemd like the hardest part of the whole project. However, it wasn’t that bad at all.

Challenge: create a shape with nearly circular base and gets thinner (elliptical) to the top.

Solution: instead of using circular sketches to guide the shape, use elliptical with varying vertical and horizontal radii. 

Since I had the freedom to adjust dimensions to my will as long as the resulted shape looked like a rabbit ear, I tinkered with different ear shape and elliptical outlines. Many combinations failed as the loft tool couldn’t generate a shape from the guiding sketches since no proper approximation lines could fit all the ellipses. 

Lesson 2: Be ready for trial-and-error when working with inconsistent guiding shapes for loft tool.

I also wanted to make the ear look like it is curving inwards (like a normal ear). To do so, I created a smaller version of the ear shape and subtracted it from the regular-sized ear.

Finally, I attached the ears to head, slightly tilting them back and to the sides.

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4. Legs, arms, and the heart

Apparently, legs happened to be more challenging to make than ears. The design method using loft tool did not work for me (to work, it would be a very tedious process that requires breaking the leg into two distinct parts anyway). 

Challenge: create a leg-like shape with a knee protruding over feet.

Solution: instead of using loft tool, create a 2D sketch of feet side view, extrude it into a 3D shape, then using fillet tool to round the edges.

This will be my first time using fillet tool in Fusion 360. It took me a while to figure out what faces to choose and what value of fillet to use to make it rounded enough to look like a leg.

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Since I just learned how to use a fillet tool, I used it to smoothen the connections between legs, ears, head, and the body. I also added a heart near the bunny's chest so it would look like the bunny is holding the heart with its arms later.

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Then, I proceeded with making arms. I couldn’t figure out an easier and better way than using pipe feature in Fusion 360 to make something that would look like an arm going from the “shoulders” to hold the heart. I also did not overthink the hand and used a simple cylinder with rounded edges. Let’s assume this bunny is of a special breed.

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5. Result

I added eyes (using spheres), eyebrows (using pipes) and front teeth (using rectangles). Then I decided to add a nose using rounded triangle to make a complete face. 

And that was it! Our Valentine gift bunny is ready to be exported in STL format and sliced for 3D printing.

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This was a fun and meaningful project. However, the bunny doesn't look very lively. I would rather say it looks like a cyborg bunny from some dystopian world. I just discovered sculpting feature on Fusion 360 that makes it possible to designing organic shapes with ease and more naturally-looking curves. I would love to try it out some day and see how well of a sculptist I am.

Thanks for following my journey and see you in the next post.

Artem