Performing surgery on a new mold. I created registration keys by cutting a zigzag into the outer edges. This helps the two parts line up more accurately for casting. I used a weitlaner retractor to hold the silicone open while I cut towards the inside, straightening out the seam as I got closer to the sculpt. It can be a bit tricky. The key is knowing where the edges of the sculpt are so that I’m not cutting totally blind. I usually take a picture of the mold set up before pouring so I have something to reference when I cut. I get better at it each time!