On the Gingerwood BB we were discussing the Rock-a-Blocks by Crafter's Companion, the pros and cons, the cost, where to get them.
I, too, wanted to know where to get them, and then I remembered that I had something that might work just as well. Now, I've had these for years, bought them on closeout. I don't know what they were called, but they were put out by Plaid, along with some very large stamps that adhered with cling. I sold all the stamps, and several of these stamp rockers some time ago, but saved two. Here are two pictures of one.
5" x 7" with a curved main base, and acrylic handle. There are grid lines on it, even angles, and 1/2" marks along the edges.
I tried it out last night with an acrylic stamp I got from Laundry Lines. This picture shows the results. And yes, the vintage look of the stamping, is accurate. The flower stamp is about 3" across.
So, if you have one of these in your closet, dig it out, or if you see one at a garage sale, grab it. They work great. I wouldn't use it for really small stamps, but those aren't the ones I have a problem with.