Design Automotive Simple Buzzer

I want to kick-off a line of small automotive sound devices by starting with a straightforward 12 V buzzer that gives a single, clear alert tone. Your job is to take the idea from concept all the way to a testable prototype that can survive the usual temperature, vibration and voltage transients found under the hood.

What I need right now
• Electrical design (schematic, BOM and PCB layout)
• Component choices that are readily available and automotive-grade
• Basic acoustic tuning so the tone is sharp and easily heard inside and outside the vehicle
• Short validation notes showing it meets the normal 9-16 V operating range and can cope with load-dump / reverse-polarity conditions

Show me examples of past work on comparable low-cost automotive or motorcycle electronics—buzzers, relays, horns, LED modules, anything that proves you understand the environment. If the collaboration goes well, I have horns and several other signal products waiting in line, so a clean, reproducible design approach here is important.

Altium, KiCad or any proven PCB CAD is fine with me as long as the output files are complete and well-documented. I can handle sourcing and bench testing once I have your Gerbers, pick-and-place data and a brief test script.

Looking forward to seeing your previous builds and hearing how you would tackle this first buzzer.