I lurve my rotary cutters. I use them for almost every project. But I do worry about disposal of the used blades. They are still wicked sharp (as we say in Boston), after all. I used to wrap them in lots of masking tape (think of being wrapped up like a rotary mummy). Then one day I had an “aha” moment. Rather than disposing of each blade as it is used, I save my old plastic cases in which the blades are packed. With a Sharpie marker, I write “Used” in large, friendly letters on the front, and I keep used blades in that. Once it’s filled up, I tape it shut and put it in the recycling bin.
Hope this helps, and Happy Sewing!