Crank up the noise!! Be the most obnoxious person at the stadium/party/ballet recital with this epic noisemaker! Just add one empty 250ml slim can for double-striker hand-cranked mega-noise action.

Read on for thoughts behind the concept and design!

AUDIENCE CONSIDERATIONS

This design was developed for the Esso + MyMiniFactory slim can upcycling contest. It's an inspiring theme, but it also comes with challenging implications! The most significant point is that submissions could potentially be used promotionally in future - imagine free giveaways with drink purchases at retail outlets. A general public audience is quite different to the audience of a 3D printing website, and we can't assume things like tools, skills, personal investment, attention, or motivation. Here are some considerations that come from that:

• Cutting and puncturing the cans is probably out of the question. While such things are fine for 3D printing enthusiasts, it presents safety issues when considering a more general audience.
• Any upcycling design should require no more than one or two empty cans. Ideally, just a single can. People are busy, and motivation only stretches so far; requiring more cans will extinguish enthusiasm fast.
• Concepts need to be immediately compelling and appealing, without needing explanation or demonstration. This is always a good idea, but seems critically important in a promotional context. People should find it novel or interesting at first sight.
• While FDM-printability is important for a 3D printing contest, the designs and concepts need to lend themselves to mass production through more traditional manufacturing methods, like injection moulding.

HOW DID THIS COME ABOUT?

Initially, I was trying for musical instruments! I prototyped percussion setups, and even made a simple kalimba. However, the walls of an empty can don't have the rigidity to make a good sound. I guess there's a reason people generally don't use them for three-string guitars, and the like. What a can is good for, though, is making a really annoying, distinctive sound when dropped, struck, or crumpled!

THE SCIENCE OF ANNOYINGNESS

In prototyping for maximum annoyance, I learnt a few things:

• The base of the can is the noisiest place to strike, being the most rigid section.
• A more substantial sound is produced if the strike is momentary, like a drum hit. The striker needs to hit and rebound, and not remain in contact, or else the sound is muffled. 
• A human hand holding the can really deadens the sound. A rigid plastic handle worked just fine, though.

So, this led to the mechanism of a crank-driven cog that impacts a pivoting striker. The striker bounces off the can and makes a noise. Now, the striker return is driven by gravity, and this affects how rapid the noise can be, and limits how many teeth the cog can usefully have. However, more noise has to be better, right?  And, so, we ended up with an independent second striker, and a split cog with two out-of-phase tooth sets, for double the eardrum-beating annoyingness!

Go forth, and make a noise!

And here's a quick video demonstration: