Need Help W/ Applying Certain Shipping Methods To Certain Items While Using Flat Rate

[SennaNight]

I sell console games and systems, and I've been trying to figure out how to set up certain shipping methods for certain items. I have the regular USPS shipping methods set up, but I also want to use domestic flat rate envelopes and boxes (which I don't know how to set up the two USPS domestic flat rate methods). Is there a shipping module for this?

Now, another problem is, if they buy a system, I don't want them choosing a flat rate envelope, since a system cannot fit into that. So, is there a way that I can choose certain shipping methods for products?

Please direct me the right path. Preferably in a dummies version. Thank you for your time.

[ultralowincome]

Yeah, I need some info on this as well. Sell a bunch of stickers and postcards, so hopefully there's a solution available