wicker shield

[Crispianus]

That is quite correct Michael but in the context of this thread it is a known technique and not a speculative one and one Spartacus was undoubtedly familiar with via his gladiator training.

Given the amount of goat hides the Roman army used I do not see they would think it too much of an expense to cover training shields.

Did ESG use goat?
As untanned hides or skins I would agree and there must have been plenty available, there are the Dura Europos shields which sound like contenders for a shield made from "Osiers" covered in "Hide", although this does not exactly describe them the techniques seems to be well known at least in the east, to someone who may not have made such a shield it might seem appropriate...

Complete Tanned Goat skin is 1-1.5 kilos per skin in its natural thickness (an average of 5) I think rawhide goat dried would be a fair bit less, you would need at least two for an oval shield(but there would a lot of waste), an untanned calf/young cattle hide may be thicker stronger and heavier (depending on the age) and would have the advatage of producing the entire thing in one piece...

As materials go, the most interesting question for me though is how many animals would be needed to produce the Hides/Skins overall and still maintain an acceptable level of breeding stock... since this is going to limit the supply, particularly when you consider how much leather is generally used in the Roman military, which in itself would require a massive investment in time to produce the tanned end product... but perhaps thats something for another thread...