The Instant Instrument Anywhere (IIA) is a small device which can be attached to any metal object to create an electronic instrument. The device uses capacitive sensing to detect proximity of the player’s body to the metal object, and sound is generated through a surface transducer which can be attached to any flat surface. Because the capacitive sensor can be any shape or size, absolute capacitive thresholding is not possible since the baseline capacitance will change. Instead, we use a differential-based moving sum threshold which can rapidly adjust to changes in the environment or be re-calibrated to a new metal object. We show that this dynamic threshold is effective in rejecting environmental noise and rapidly adapting to new objects. We also present details for constructing Instant Instruments Anywhere, including using smartphone as the synthesis engine and power supply.