This is an app that I have created, simply named "Spammer". Not that I condone doing this a lot, but this app is able to send large amounts of spam to any phone number you choose. I am fairly new to android app development, so this app is still a work in progress. Feel free to test, and hit the thanks button if you enjoy the app.
Ability to send SMS (Carrier and Google Voice)
Material Design (After Android L is released)
The apk file is located in there
TESTED USING NEXUS 5 AND MOTO G