Hi I bought a Strat awhile back that had a 1 ply pickguard. I want to keep my Slanted Pickup because it's sort of a Hendrix Tribute and I'm trying to find a Right handed 3 Ply Pickgaurd that has a slanted Pickup hole and I have found one but it's pretty expensive for a Pickguard I might turn to it for my last resort and yes I need this plus I'm puting new pickups in so I might as well get a 3 ply as well if anyone can point me in the right Direction thanks
any single coil strat pickguard has a slanted bridge pickup

try guitarfetish.com or stewmac
I think he means a reverse slant. So the bass side is closer to the bridge.
They are usually about the same thickness, depending on what material they are made from. Around 1/8th inch thick. But 3-ply refers to 3 thin layers glued together, that's how they get the stripe. Like White/Black/White, ex:


Your pickguard is 1-ply, but it is the same thickness as a regular 3-ply, only difference is you don't have the stripe.

Anyway I have a pickguard business and can help you out if you need, link in sig