How to make transparent hats?

[Le' pootis pow | Pant shitter]

I need help for a visor but i cant figure out how to make it transparent!

[nerdqualquer]

You need to create an alpha mask, it need to be in alpha channel from your main (tga) texture file, them you check the "translucent" checkbox on TF2 model importer, the alpha channel will be automatically applied as transparency mask.