Dean Ing's book _Pulling Through_ has instructions on both an air filter made from rolls of toilet paper (with pump) and plans and templates for a homemade radiation detector. (At least, early editions had these. They're probably online, anyway. Just look for Kearney Fallout Meter.) The last third of the book (the first two thirds are a novel) is about nuclear war survival.

This was originally published in 1983, but nearly everything in it is still valid.