Sorry it has been so long for reply.
The plastic landwire mesh is what you're looking for. I believe thee larger size grids are what is used in cage making, while accessories (such as wheels) are usually made with the smaller sized grid, I don't remember the actual sizes though.
From reading another post, I've heard that the smaller size, probably what you're looking for can be found where they have gutters or covers you put on gutters, though I've not actually been to check it out myself. I actually have some larger grid that I've made some cage tunnels with, I know it's larger than the mesh size used in wheel, but not sure if it's as large as used for cages. The tunnels I've made seem to be ok.