Loudspeakers

Finland

We would need a really small speaker that would fit into the bottom of a frisbee golf disc. The dimensions could be approximately 3cm in diameter and as lightweight as possible. The speaker should be as thin as possible. The sound should be audible as a loud beep at least 20m away. It needs to be waterproof. The speaker could be connected to either a phone via Bluetooth or with a small remote control. Could you make something like this? And price, what would you think that what will this cost?