With this simple tutorial, a little time and the Raspberry Pi (any board, indeed), you will learn how to create thanks to a Python wrapper for the Twitter API called Twython, a fantastic bot that post for you whatever you want. It is very easy to implement, really.
PS: Today is a special day: My daughter is 6 years. Laura, if one day you read this, from here I wish you an amazing day with your friends and family. We love you and we are very proud of you.