grip; $25-35 for a pistol or a Thomas grip.
Warning- cheap cutters break. Snap right in half. I learned that the hard way. ;)
Toyo Pistol Grip cutter $33
Toyo Acrylic Pencil Grip cutter $27
Toyo Brass Pencil Grip cutter $34
Toyo Thomas Grip cutter $30
Now you'll need some tools for breaking the glass. I suggest these
Studio Pro Breaker Grozer Combination Pliers $13
If you have a Hobby Lobby Store, you should be able to get them there.
If you want to break mosaic pieces, you'll need a pair of running pliers, or
"runners," as they are sometimes called.
Studio Pro Running Pliers $13
Also found at Hobby Lobby. You might even check your local home
improvement/ hardware store.