I'm currently modeling some cold war soviet radar units and have noticed that the feet of the leveling jacks rest on stacks of thick sheets/thin blocks about 2' square and 3-4" thick. No evidence of handles or straps on the sides, and the stack so neatly, I suspect they have bumps on the bottom and divots on the top. They seem thick for wood, concrete would be heavy, and they're too thick for steel.

Can anyone tell me what they're made of so that I can model them correctly?

Thanks in advance,
Morgan

Can you post a picture of what you are specifically talking about?