Prototype needed for tiny electronic wearable

In short, its a wearable that vibrates according to set time intervals to be worn like a fashion accessory or attachable to existing accessories.

Function: Contains one button. Button to set time intervals - cycle through intervals with short button press. One press = 10 mins, Two consecutive presses = 15 mins, etc...up to 60 minute intervals. Corresponding feedback 10 mins = 1 pulse , 15 mins = 2 pulse, etc...

Long button press = turning off and on

Rechargeable battery with USB. I would like to have at least 1 week battery life or more.

Water resistant

The smaller the better. Use smallest components possible. Goal for this prototype is to determine the smallest size possible including all the components so that I can have this data to determine end product design possibilities.