Draw a line on the tile to indicate where you'll make a cut. Trace casing designs on the tile using a scribing compass to remove the tile's waste material, and place the tile next to the casing. Slide the compass along the casing to leave a traced line on the tile.
Equip the oscillating tool with a plunge-cut blade featuring a diamond- or carbon-encrusted cutting edge.
Put on your safety glasses, dust mask, and ear plugs. Turn the oscillating tool on. Hold the tool with both hands and gently plunge its blade into the tile material.
Angle the oscillating tool so that the blade cuts in a forward direction. Follow the line working at a slow, steady pace.