Incremental robotic sheet forming is used to fabricate a novel cymbal shape based on models of geometric chaos for stadium shaped boundaries. This provides a proof-of-concept that this robotic fabrication technique might be a candidate method for creating novel metallic ideophones that are based on sheet deformations. Given that the technique does not require molding, it is well suited for both rapid and iterative prototyping and the fabrication of individual pieces. With advances in miniaturization, this approach may also be suitable for personal fabrication. In this paper we discuss this technique as well as aspects of the geometry of stadium cymbals and their impact on the resulting instrument.