Avocado - Design of the Second Prototype

 My vision of developing the Avocado came from my desire to build a percussion instrument that could help users relieve stress. For information about my first prototype, please visit https://marchtoyourbeat.hk/from-jamming-to-the-avocado/. 

After constructing my First Prototype, I identified two limitations with the design. Firstly, the styrofoam shell was too rigid. It failed to compress fully even when the user held tightly on the instrument. Secondly, the design was a two-dimensional sandwich structure, which meant the instrument could only be compressed in one direction. 

To improve on the Avocado, I decided to construct a second prototype. To solve the first problem, I decided to utilize soft sponges as the outer shell. I experimented with sponges of three different levels of rigidity. I allowed a sample of special needs students to feel those textures to discern which one they liked best. Over half of them preferred the sponge with medium hardness, so I went with this sponge as the outer shell. 

 The Design Process 
 The Actual Building of the Second Prototype 

I fashioned each half of the Avocado from a larger piece of styrofoam with a pair of scissors. I then hollowed out the inside to create a chamber. I filled the chamber with a mixture of large hollow brass beads and smaller stainless steel ball bearings. I figured that by using a large hollow bead, the sound produced would possess more resonance. I also experimented with different glues for putting the two halves together. When the shaker is shaken, the rattling sound is contributed by: 1) the sound of the small bearings colliding against each other, and 2) the sound of the small beads hitting against the large one. 

When the user becomes stressed and squeezes this prototype tightly, the inner chamber collapses and beads would be prevented from moving and colliding with the larger bead. Thus, no sound would be produced. With this new prototype, the shell is able to be compressed in any direction, making it a more effective stress reliever than the first prototype. Going forward for my third prototype, I hope to experiment with different types of beads, with varying degrees of hardness and materials, to optimize the quality of sound being produced. 

Testing the Second Prototype with the Students I Served 
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