2026-05-27 (W) Grindfest2026 Gumball machine COMPLETED

My wife and I found a commercial gumball machine at a thrift store, and we both wanted to turn it into something that dispensed baubles at Grindfest. It did not come with a key, but I was not worried about that. I should have been concerned. I spent an hour picking the lock, but it was a double-sided key, which took a moment, and every time I aligned the wafers, it could only manage a quarter-turn. I gave up and drilled out the lock. The shaft running down the middle held everything together, and it was a standard 1/4-20 rod, so it was no trouble to find a nut to reclose the machine. I went with a threaded wood insert because I could remove it with a hex key, which made it very narrow compared to a coupler nut, which would have required gripping it from the sides.

I modeled a few baubles to go inside. The first was a 1" sphere, which I printed to test if that was the correct size for the machine, but it turned out that I should have been using 1.25" spheres, which I confirmed with a second revision, and then ordered the appropriate vending capsules so I can add stickers and whatnot to the machine. I printed some more spheres that can be their own baubles since I included "Grindfest 2026" in hollow text. Adding the text as a concavity was probably a mistake, since it required more time and filament to make solid walls all the way from the center to the top, whereas a hollow sphere with a few alphanumeric characters at the top was quick and light.

Each time I wanted to open the machine, I fumbled with the hex key, so I modeled a new bauble with a hexagonal hole at the bottom to accept a 1/4-20 bolt head. With this, I could install the coupler nut and a short bolt directly onto the shaft and loosen it without tools. The decorative top would not provide any security, but I have also been printing quarter-sized discs with "Grindfest 2026" that will operate the machine, so it is really a giveaway machine, and I am not worried about someone opening it and taking a free item.

Commercial gumball machine with printed baubles

The rest of the Grindfest posts have been arranged by date.
First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7
Completed projects from year 8
Completed projects from year 9
Completed projects from year 10
Completed projects from year 11
Completed projects from year 12

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2026-03-18