Gandhi said, "My life is my message." Nothing can be truer than that statement except maybe, "My life, with Christ lived through it, is my message." Our passage refers to it as "heaven's poetry etched on our lives". Grace isn't just something we "get" - it is something we see affecting our lives, changing our testimony, and actually turning our lives into a message from God's hand itself. An author doesn't set out to "just write" - he has a message in mind as he begins the task of creating the masterpiece he will one day finish. I imagine God to be quite the same as an author - a mindset for what the end result will be, creating scenes all along the way, orchestrating the "building of the story", until we see the climax of it all when he loudly declares, "Well done, my good and faithful servant."
We are the "product" of his hand. A product is meant to be used in some fashion - it isn't just created, tossed aside, and then forgotten. God's intent for each of us is to become the thing he uses to declare the beauty of forgiveness, the bigness of his grace, and the boundlessness of his love. As the products of his hands there is nothing "ugly" about us. God doesn't create ugly things - evil does. Evil is not part of God's make-up, so it is impossible for him to produce a product which is less than perfect - as he is perfect and all he does is perfect!
A product may also be produced simply because of the environment it is within. For example, diamonds are not "natural" - they are formed by the pressure placed on carbon deep within the earth. Eventually, they rise little by little to the surface and are mined. Even in their "raw" state, they aren't all that "beautiful". It takes more and more cutting, fashioning, and specific application of skill to produce the diamond we will proudly wear. Sometimes I think we are quite impatient when it comes to seeing "God's product" produced within us. We don't realize all the work required to bring the greatest amount of beauty from each of us!
Etching may be accomplished by the placement of acid upon the surface until the surface is altered by the application. The acid actually leaves a mark which was specifically "purposed" to be there. Acid isn't all that "palatable", but when it is applied by a skilled craftsman it produces a beautiful work expressive of something the craftsman saw as lending beauty to the object.
God may use a little pressure, and even a little bit of what seems to "sting" or "burn" a little to produce the most beautiful things in our lives. We shouldn't resist this process, because it is the process which produces the object's beauty! Just sayin!