CB Range discussion

Hello everyone. I’m a newcomer to chastity devices!:) I just got my hands on a CB6000, but alas, it’s already giving me trouble. I’ve gone with the biggest ring available, yet it feels too tight for me; within minutes, my skin starts to change color and I have to remove it immediately. To be direct, I carry quite heavy testicles in that area, so even when pairing the largest ring with its spacer, my scrotum begins turning a purplish-blue hue—a clear sign of distress. My main question is whether anyone knows where to find larger rings than the standard one included with the CB, or if there’s a DIY method for resizing it effectively. I appreciate any guidance you can offer!:)