Sorry, I wasn’t subscribed to the thread so I didn’t receive notifications for new replies. Zebralight uses two styles of bezel. The SC64, H600, and SC53 series have the easy to open bezel, but the SC600, SC700, etc. require more effort because the bezel has no lip underneath.
For those lights, the tool need to be thin at the tip, but solid enough you can actually press down on the o-ring and force it under the edge of the bezel. It can also be helpful to gently tap it under, but you have to be careful about the angle and amount of force because it’s easy to break the edge of the lens. Wood carving tool kits with a tool of the style shown in moridin’s thread here are readily available on Amazon, but they typically need further grinding to refine and maintain the shape. You can also try something like a very thinly ground flat screwdriver, but it usually leaves more obvious cosmetic marks like the bezel shown in the photo above.
What LED are you planning to put in the SC700d?