I have mostly acrylic stamps and when I've finished with a stamp, I throw it into a bowl of slightly soapy water. If I'm using Stazon, I clean with Stazon cleaner first, then into the water. Keeps my little images in one place and everything clean.
I have a couple of large blocks and one each of a few smaller sizes, so I don't need to remount all the time when I'm using more than one image.