I always recommend that people should create their own tools, and do their own legwork. You’re quite right that in creating that piece yourself, you can put a great deal of intent it. That doesn’t make it strictly better- it only means that your physical and energetic actions are in sync at the time of creation.
Remember, the idea that physical and energetic planes are at all separate is only a mnemonic device. Time and space are only as limited as our perceptions of them. In order to get he same result out of a piece you didn’t make, I would suggest going through the motions of having already created it yourself. The more you know about the processes used to make it apart from you, the easier this will be. I’ll use the example of a cast pewter necklace below.
Cleanse out your talisman thoroughly, and sync with your deeper state. See the talisman you have before you, and all its aspects, as a design on paper. You have the final product in your mind’s eye (And in your physical hand), but it is not yet made. Right now, you have only the beads of pewter to be cast into your Talisman.
Select the wax you’ll use to carve the shape of your talisman. Feel the smooth mass beneath your hands, the comfortable handles of your tools. Carve your talisman into shape, shavings at a time, before pouring the mold solid around it. Heat the furnace, and bring your pewter up to temperature. Use the heat of the furnace to melt the wax from the finished mold, leaving only the hollow in its place. Melt your metal in the crucible- feel the heat of it, the weight.
Speak whatever words you need to at this time, to whomever you will, as you pour molten metal into mold, solidifying the talisman’s body into shape within. Break the mold, releasing your finished talisman. Polish and bless it, do whatever finish work you like. Then, repeat the actions of blessing which you have carried out in the physical, as well.
Everything that is before you is of your creation- half the work is reminding yourself of the power you possess. It’s easier to do this if you physically made something with your own hands, but having physically made that thing with someone else’s hands is very nearly the same.