Maple is pretty hard, but I imagine it would still get chewed up. I have used an unopened can of extract to crush grains with great results.
I cannot imagine making a crusher out of wood. It would eventually get chewed up and become useless. I'm making mine out of knurled steel, and it should last forever, but the tools are harder to come by (I work at a machine shop, so I'm good).
If you can find a metal TUBE (Large diameter pipe) you could use that as a sleeve for a wooden roller. This would omit metalworking tools from your requirements, and still give a durable roller. Use a larger diameter roller if you are not going to knurl it. It will help grab the grain and pull them into the crusher.