Launched my first physical product business last week: Hoppy Press [0].
I'm not shipping heavy components (opposite, actually: 12.5 ounces/~350g) so I don't have much advice for you on that front. I would like to share one lesson that I learned so far: the costs of shipping the actual shipping/packaging supplies was a bit more than I estimated. 40lbs of Kraft paper doesn't ship free.
Right now we are only offering USPS for shipping. We looked in to Amazon Fulfillment which is priced appropriately and would be good for a "hands off" approach. However, we like being able to include hand written notes and other gestures when we ship to our early customers.
Good luck!