If you think I'm going all over the place, that's kind of the point. I would like for you to employ magickal thinking. Look at objects with new eyes and see not just what they are, but what they could be.
You might be thinking the spell would be further changed if the threads ran in reverse. Correct. Our design would also change if we went from string art to actual stitches because a pattern would then emerge on the back of this design. That could be useful if you needed support or an infrastructure or even a network of communication.
If I was going to use this as a spell, I'd start with the original design. I'd make a list of what I wanted. I'd try to assign colors to those desires. Then I would pick a day, moon phase or time. I don't get too hung up on the when of spells because there is always a good time to begin a work. Let's say you really need money but the moon is waning. Just start your spell after the half hour. If it's 2pm, wait until 2:30 when the clock hands are moving up. Or you change the wording a bit and instead of asking for money, ask for debt to decrease. Then 2pm is a great time to start your work because the clock hands are moving down. Timing can be very helpful but I don't put my life on hold while I wait for the right moon phase.
Since I am a person who sews, my spell would be worked in textiles and fiber, but this could all be drawn on paper with colored pencils or markers. After I had chosen colors, I'd chose threads or yarns. I would cleanse the canvas I was working on. I might place some stones on it or leave it in the moonlight to charge. I would charm my thread, filling it with my intent. I might chant before I began sewing. I could chose to work in a particular place like the porch to represent a between place or the living room to represent home and family. While sewing, I would try to focus my thoughts on my goal. I might listen to certain music or light a candle.
If I needed to stop before I completed the project, I'd carefully put everything in a special box or bag to contain the magick until I was ready to release it. Each time I worked on it, I'd try to do things the same way, same music, same place, same candle, same chant.
When I finished the project, I'd empower it again. This might be another night in front of the window to catch moonlight. It could be me singing over the piece. I might leave it in a stone circle for several days. I could sprinkle herbs around it.
After the project is finished, it should either be given to a person so it can begin to work, or it needs to be used immediately. If it was something meant to stay in my home, occasionally I would rework the spell to keep it going. Eventually, the item might begin to have a 'life' and would need to be 'fed', this could be sprinkling it with water, giving it blood or honey, or it could mean placing crystals or live plants nearby. The item will tell you what it needs.
If we were using an actual transmutation circle, our spell would go the same way for the most part. We'd think of what we needed, find symbols to match those intents, then chose colors, then start drawing on either charmed paper or we'd chalk it on the ground. The difference is transmutation charms aren't meant to be long term. They seem to work better if the destroyed to release the magick either by burning or the rain washing away the chalk drawing.