How To Design :

Problem Statement	Explanation
Parking Lot Application	Build a parking lot management system, Solution can be found here
Centralized Logging Application	Build a Centralized Logging system to overcome the debugging problems, Solution can be found here
URL Shortner	Build a URL Shortner system like Bit.ly here
Tiger Card Fare Calculation Problem	Solution can be found here for a fare calculation engine built using SOLID principles etc.