Introduction

This week’s challenge was to design and 3D print an impossible object something that couldn’t be made by traditional manufacturing and make it small enough to live inside a plastic gumball capsule. The guidelines were to create five objects using two printing methods while maximizing the space inside the capsule.

At first, I didn’t have a specific design in mind. I just knew I wanted something with movement articulation was non-negotiable. So, I began my hunt for inspiration the way all great modern makers do: by getting lost on Thingiverse and printables.

Step 1: The Search Begins

I went through articulated designs, hoping something would spark joy. That’s when I stumbled upon the goofiest little jellyfish with segmented, floppy tentacles and a weirdly expressive head. It looked equal parts robot, creature and toy and it instantly became my top choice. Finalized the one from printables and the link is as follows: https://www.printables.com/model/1200010-swimming-articulating-jellyfish-cartesian-diver/files

Now came the math: the gumball capsule’s internal dimensions measured 47.40 mm in diameter and 51.00 mm in height. To get the jellyfish to fit snugly but not jam inside the capsule, I brought the .stl file into the slicer and scaled it so that no dimension exceeded 50 mm. (Side note: I could only figure this out using inches in the slicer, which was slightly chaotic, but it worked.)

Step 2: Printing—Battle of the Machines

Armed with the file and scaling complete, I went with a split printing approach:

• Three jellyfish printed on the Bambu printer

• Two jellyfish printed on the Prusa

Bambu Round:
I loaded the file onto Printer #7 and sliced it with supports the first time to see if it works. Then realized I don’t need supports otherwise it would complicate my design so went ahead without them. The print time came out to 4 hours and 20 minutes for three jellyfish. Everything looked promising.

 

Prusa Round:
I manually loaded the file into PrusaSlicer, scaled it to match the Bambu version, and sent it to the printer via SD card. The Prusa estimated a slightly faster print time 2 hours and 48 minutes for two pieces.

Step 3: Results & Surprises

When the Bambu prints finished, I was delighted. The jellyfish looked fantastic, and the joints moved perfectly. Each one fit beautifully inside its gumball capsule and watching them wiggle inside the plastic shell was surprisingly satisfying.  To my surprise, the Jellyfish also floats off to the top when you add water to it. Fun Fact!!

The Bambu prints were the successful ones here. The surface finish came out smooth and clean, with minimal effort during post-processing. In contrast, the Prusa prints, while still decent, had fine strands and imperfections popping up occasionally, requiring constant supervision during the print. Support removal was a little tricky on the first and the overall quality just didn’t match the polish of the Bambu prints. Big thanks to Katherine Sammy and my Berlin-based friend Sanjeev for their help figuring out all the little workarounds and loopholes, I couldn’t have done it without them!

Neither printer was perfect, but each had its moment.

Step 4: Post-Processing & Final Touches

I kept post-processing to a minimum. I removed supports, gave the Bambu prints a quick sand where needed and dropped each jellyfish into its capsule. The tentacles looked good so I kept that at bay.

Final Thoughts

This project checked every box for me:

• Articulated movement

• Efficient scaling

• Comparison between two printer types

• A goofy, delightful end product

While I didn’t get to experiment with SLA printing this time (thanks to printer downtime 😞), I don’t think it hurt the outcome. My FDM prints came out clean, wiggly, and totally gumball-worthy.

This experience has me looking forward to printing more whimsical, personality-filled parts not everything has to be functional or serious. Sometimes, you just need to print a tiny jellyfish and call it a day.

Cost Analysis:

Material (PLA):
~$0.12 per jellyfish (5g of filament @ $25/kilo)
$0.60 (for 5 units)

Machine Time:
$2.00/hour × 5 hours (FDM printers, electricity + wear)
$10.00

Labor:
$15/hour × 2 hours (setup, supervision, post-processing)
$30.00

Packaging:
Gumball capsules @ $0.15 each
$0.75

Post-processing supplies:
Sandpaper, adhesive etc
$2.00 (estimated)

Total Production Cost:
$43.35 (for 5 units)

Unit Cost (Per Jellyfish):
$8.67 per unit

Clean working space: