Dritz has a rotary cutter that sells at JoAnn that I have truly appreciated. It has a setting for single layer fabric, or multiple layer fabric, and a lock blade down. When the lock is removed and put on one of the settings, the blade is not exposed. When you place the cutter on the fabric and press to cut, the blade is then exposed. It is a dark Royal blue in color. I just wish I could find it in the smaller blade size, as the cost of the blades go up with the size of the blade. I use the 45mm.
Marsha