I personally have a key ring that can connect to my belt via carabiner ring. On that I have a "primary" ring that I always keep attached to it - the two for my house, my car, and my bike. I have a separate ring that I can clip on the carabiner that I can unhook from it for my work keys. I have another ring for my parents and my in law's homes which works since they both live out of town. You may also consider reducing the number of keys that you need to use, much less carry. For example my shed has a pass-code lock. At the very least you may want to consider re-keying or replacing your locks to where many of them share the same key. That could help reduce your volume.