Hand-hammered copper mechanical crab (somewhat like a push toy) with wheels & snapping claws

Does anyone recognize who the artist could be for this novelty piece? It's like a grown-up's toy with a very elaborate set of linkages underneath (picture #2) that make the claws snap and the legs move up and down as you push the crab in a scuttling motion left or right. It looks like something that probably would have been sold at a high-end arts and crafts fair. I have no idea of date, maker or region. I presume it was made in the US but don't even know if that is true. Other than the ball bearings used for the eyes, it's 100% handmade from wire and copper sheet, including the wheels and the linkages (which are made from bent and twisted heavy-gauge wire). There is an "R" written in magic marker underneath (picture #3). Additionally, something that looks like capital "F" or "S" plus a script "e" with a long tail and either "37" or "31" is scratched over the black "R". Size is 8x12x3. Any insights are appreciated!