Classics do not have lips for caps, or even lips that "could’ be used for caps. I suspect these are gently lathed to create a surface for mounting the glass dome.
That is exactly correct…each side of the Classic is mounted on my lathe, where I cut a precise 1.5" diameter counter bore about 1/16" deep, which is about as deep as I can go without cutting through. This particular process does not use a captive “cap”. It is a piece of dome shaped glass, with a paper cutout attached to the bottom that is then permanently glued into place. The glass gives the image a pretty cool magnified look. Don’t think there are many (if any) take-apart aluminum yoyos that would work with this process.