“Safely” doesn’t exist for self-inflicting scars.
A fresh and sealed razor blade would minimise infection risk. Plus alcohol based rub applied before incision, and local anaesthetic. Hair around any incision site is a risk for infection.
So in other words, don’t do it irl.
Even with sterile surgery, I still got an infection bad enough to keep me in hospital an extra week, and another scar crash landing as a result of the infection (a staphylococcus infection).
Pain is all relative, and I don’t have “normal” pain sensations now. I did refuse all pain meds 3-4 days after after having my sternum cracked open for a second time, but that was because I kinda got hooked on morphine and propofol the first time.
DO. NOT. TRY. TO CREATE. SCARS.