JumbleDuck
Well-Known Member
The best material is depleted uranium, and it has the advantage that it is self-drying and keeps your feet warm.
A pedant writes ...
Depleted uranium - typically 99.7% U238 - is actually not very radioactive at all. The dust is a bit nasty, as are most heavy metal dusts - but the hysteria so often seen about the solid metal is a sad reflection on the state of science education. In my youth I went to see a travelling exhibition about nuclear power, put on by the Science Museum. It included a nice big chunk of DU which you could pick up and handle. Try doing that nowadays ...