Smartband with Arduino

i guys, i want to build a smartband to help me waking up. I am not a morning person, and waking up every morning is just a pain. I saw some of the new smartbands from sony or other comanies they have a nice feature, a vibrating alarm. You set the alarm from your phone, and instead of ringing it will make the smartband vibrate. So i was wondering, what if i will make a little custom arduino board (maybe with the attiny or a atmega) that has a bluetooth connection (2.0) with the smartphone (and why not, maybe even an oled display) and it will just vibrate at the right time?
P.S do you have any idea on how to make the enclosure?

I suspect this project isn't worth starting.

Firstly, you can buy watches with alarms with vibration function for less than the cost of the components you would need to build this.

Writing apps for phones is not trivial and is generally more complicated when you want to write stuff than runs in the background eg an alarm

Don't even contemplate an iPhone app, it cost $99 per year from apple just to deploy to your own phone, and you'd need a new ish phone e.g. 4s or newer and have to use a Bluetooth low energy module at the arduino end.And without a mac its hard to deploy to iPhone