Similarly, honeycombs formed of resins or plastics can be employed, these being fabricated from such polymers as high density homo- and copolymers of polyethylene (e.g., ultrahigh molecular weight polyethylene), chemically inert fluorocarbon polymers such as Teflon polymers, and high temperature plastics such as formaldehyde-phenol (Bakelite??? plastics) may be selected.