I actually have no idea
This depends on the type of water used to make ice.
wood
Well, first thought would be keep in in the freezer. Covering the ice cube with an insulating material would help, sawdust or woodchips is what they used to use many year ago.
Squares
punett square
It is water frozen in a shaped like a cube.
A square
petroleum jelly, stick inside the cube
The mass of a styrofoam cube can vary depending on the size and density of the material used. In general, the mass can be calculated by multiplying the volume of the cube by the density of styrofoam. The formula is mass = volume x density.
The same as the container that's used to hold the water while it freezes ! An ice-cube can be as small as 1 inch square - or hundreds of feet !
Beach scarves make good towels, but check the material first to make sure it can handle the water.
Copper used to be very common, now many kinds of plastics are used. PEX is one of the most popular.