[gravitronic]

Hi, you can set up weight-based shipping rates so products over a certain weight have different shipping rates applied. You just need to tell Shopify the weight of those products. http://docs.shopify.com/manual/settings/4-shipping/4-shippin...

If that's not good enough there's apps like Better Shipping that can set up more complex shipping rules - http://apps.shopify.com/better-shipping