Number models with a few maths symbols.
If used please credit me in some way, big or small, although it is not necessary.
Extract to cstrike folder
Each model can have 3 skins. There is an example of that with the 0 model.
If you look in /materials/models/numbers you will see 0.vmt, 0\_alt.vmt and 0\_alt2.vmt. This is the same for the other numbers, so just copy the current 0\_alt and 0\_alt2.vmt or make your own vmts, but they must be named modelname.vmt, modelname\_alt.vmt and modelname\_alt2.vmt. For example, creating the alt skins for the "plus" model you will need to make a plus\_alt.vmt or plus\_alt2.vmt and choose which vtf to use in those.
They can only be used as prop\_physics. If you don't want them to move, go to the Flags tab and tick "Motion Disabled".
I apologise for the minus, I don't even know why I made it. The multiply symbol could also do with having the edges slanted too, but you can make that in Hammer too, like the minus.