$2 for 10 PCBs prototype: https://jlcpcb.com

Make a DIY wifi smartwatch using OLED display for under 20$. The esp8266 module has an inbuilt wifi module which allows the watch to connect to the internet. You can control other electrical appliances remotely through the internet from anywhere in the world. This is possible due to IoT services.

Materials :
ESP12-E(ESP8266) https://amzn.to/2DqS0TP
OLED Display https://amzn.to/2R4iSN0
3.7-volt battery https://amzn.to/2HnI9lr

Buy 10 PCBs at $2 from https://jlcpcb.com
Upload this Gerber file and checkout
https://drive.google.com/open?id=1sab...

PCB Design Credit :
The Technowright