All I know if is how to access the source sdk, nothing else... I'm not sure if it's what you're even looking for, since I'm not a modeler at all. Right then, the source sdk is accessed in steam, under the "tools" tab. You'd have to have TF2 I'm willing to bet though.

Hope that helps!

Found it thanks!

Open the Community window and click the Tools Tab. There's a bunch of crap in there you can fiddle around with.

Found it thanks!