I don't think there are any... I've been looking too. I'll probably end up making my own by scaling the screenshots here to my measurements and tracing/approximating them on paper. It'll be a lot of trial and error, though.
Pretty much all of the ones I've seen are made using 1/2" EVA foam flooring tiles. I literally just posted a thread for a site that's having a sale on that particular kind and size. $20 gets you almost all of the materials you need for an N7 build.