I love how much I've seen this activity around lately. The kids loved doing it. Here's how we put our own little Montessori twist on it.
Large Kid Friendly Ink Pad (green and red)
Christmas Stamps (we used the clear ones)
Paper Roll (or just lots of paper)
We taped the actual stamps to the rocks so that it gave Indie a good grasp. I really liked the texture and weight the rocks gave the activity. It also allowed me to take them off easily and wash them up so I can use them for something nicer if I need.
I rolled out the paper on the table and let them go at it. They had a really good time.
I can't wait to get some wrapping done so they can see all of their handiwork :)