Portable Trombone Warmer Prototype Development

I need a working proof-of-concept for a compact device that pushes temperature-controlled air through a trombone so the horn reaches and stays at its ideal playing warmth. The first build must run from a rechargeable battery, couple to the instrument through the mouthpiece receiver, and hold the bore at roughly 30–40 °C (86–104 °F).

Core functions to engineer
• Rapid-heat mode that brings cold metal up to temperature in minutes, then a maintenance mode that keeps it there with low power draw.
• Stepless or stepped temperature adjustment, quiet blower, and user controls that give tactile feedback without audible clicks.
• Safety features—over-temperature shutoff, short-circuit protection, and proper insulation around the heating element.
• A form factor small enough to fit in a gig bag while still allowing good airflow.
• Clean, modular electronics: microcontroller, thermistor/thermocouple feedback loop, and off-the-shelf or easily sourced components.

Deliverables for this phase
• Electrical schematic, PCB or breadboard layout, and full BOM.
• CAD for the housing and the mouthpiece-receiver adapter.
• Firmware source code with documented control logic.
• A functional prototype demonstrated via live video (or in-person hand-off if practical) that meets the temperature, noise, and safety specs.
• Brief test report outlining warm-up time, temperature stability, and battery life.

Preferred background includes hands-on work with low-voltage heating elements, small centrifugal or axial fans, Li-ion battery management, and rapid prototyping tools such as 3D printing or CNC. If you can iterate quickly, explain design trade-offs clearly, and help forecast the path toward a manufacturable unit, let’s move forward.