I may have another smaller project I would like for you to work on also. I should be really simple for you to build.
Basically you will press a button and your phone be set to silent for 5 minutes. After 5 minutes the volume will be reset to normal.
If you press the button twice, it will set to 10 minutes. Press it three time and it will set 30 minutes. press it 4 times and it will set for 1 hour. Press it 5 times is will reset turn off.
It should be built for android, ios, and windows phone.
Let me know your cost and time line.