For users of jamf Pro (formerly JSS) as their MDM solution, students misplacing devices can be a real pain! With my app, its a simple process:
1) Provide the URL and User information for API access
2) Either scroll through or type a search term
3) Click "Enable Lost Mode" or "Disable Lost Mode" to make the device start singing.
I hope this is as useful for you as it has already been for me!
This app NEVER sends any of your information anywhere except the JSS server URL you tell it to. All settings are stored on the device, nowhere else!
Visit my github (https://github.com/sreyemnayr/jss-lost-mode-app) to see the source code or to run/tweak it in Pythonista.