WordPress Default WYSIWYG Editor customization


I am an HTML/CSS/Javascript developer whom is familiar to WP/PHP and has developed a handful of wordpress sites, nothing super customized. This is my first major Theme/Framework which is being built over at WP-Engine.

My Question:

I want to add a button to my wordpress multi site WYSIWYG editor which when pressed would insert an HTML snippet, honestly I want to use the dropdown because I want to create 10-20 snippets for clients to insert. This is to avoid clients needing to know HTML to use the WP-Admin. I have been searching for some plugins and then remembered that part of WPMUDEV services was support from WP-Ninjas.