What types of packing materials and boxes do you use to ship road signs in the mail?
Usually I cover the sign with newspaper and just wrap it in a cardboard box that is the size of the sign. Generally I hang onto boxes that I get from other shippers and just re-purpose them when I need to send something.
I am looking for about 100k aluminum signs (http://"https://municipalsigns.com). This company told me they ship their aluminum signs in bulk through trains and that it is the cheapest way to do it unless you go outside the country then trains are no longer a viable solution.