How can I cover radiator heater and still the the heat out?

I've seen some nice screens/surrounds made using wire mesh and wood. I also think it would look really neat if you used a fancy door mat instead of the mesh or look for some retro wrought iron at the rehab store. Good luck!

You can cover them with a metal cover that is well ventilated but not many other materials are suitable

Metal is a typical material choice. make sure it's large enough to not rub and is well ventilated to allow air movement across the heater

Whatever you cover it with would have to be fireproof and allow the heat through.

Google it. Good luck with that oy

old radiator covers are easy to find or I have seen people use metal screens from a fireplace

Make a decorative box using lattice panels. That way, it is covered, but the heat can still come through the openings on the lattice.

wood frame with metal meshing comes in various designs

Your very welcome.