This is an instructable for a cheap auditory disc golf disc locator using a key finder! I'll show you my idea and procedure, but it could certainly use some improvement. Be creative and make it more robust it if you like the idea.
Step 1: Materials
The obvious one is the disc golf disc, but the crux of this project is a wireless key finder. You can pick them up at your local hardware store and every one that I saw was under 10$. I bought a less expensive one but I'm sure the more expensive ones are louder and have a longer range which would be nice.
Step 2: Modify the Key Finder
This step is pretty straight forward, we just want to make the part of the key finder as small as possible. I stripped off the casing with a screw driver and then the electronics in a thin layer of tissue paper and tape to provide some support for impact. You want to keep the piezo disc (or speaker) as open as possible so to maximise sound. I kept the plastic part of the packaging and cut it down to use for a little more protection for our tiny noise maker.
Step 3: Gut the Disc
I anticipated this part of the project being pretty simple, but it was surprisingly frustrating. The goal is to take out just enough of the rim of the disc to slide the key finder into with out punching a hole through the disc. I used a drill to loosen the plastic and then dug it out with a small wood chisel. This technique was effective but the plastic does not really drill out and only kind of separates. Feel free to experiment and figure out a better way. Also note that taking out this section of the rim had almost no effect on the flight of the disc which was a pleasant surprise to me. (The key finder adds up for just about all of the lost weight and in the end the balance of the disc is not even compromised.)
Step 4: Assembly
As you may have guessed the last step is to secure the key finder into the gutted section of the rim. I simply did this with some masking tape as I wanted to keep the key finder removable so I could tweak this design in the future. There's no wrong way to attach the finder, just try to keep it as light as possible with minimal amount of covering over the piezo. I kept a little cut out section near the on/off switch and I highly recommend you doing the same.
The finder had a true range of about 50 ft but loud areas outside significantly lower this to an effective range of about 20ft. If you mostly play in very quiet areas this finder may be for you. If your course is busy and the birds are always chirping you may have to find a way to amplify the sound. In the end this was a great way to locate which pile of leaves your disc is buried in in the fall but I still have been hesitant to perform the operation on my better discs.