Hi MMD,  After many months and dozens of email I have yet to locate
a manufacturer or a supplier of 3/8-inch D-rings.  These D-rings are
the type used by many piano roll manufacturers for the pull tab.

I have located a vinyl cloth material and have purchased a die
cutter for the tabs but I cannot proceed until I locate a D-ring
source.  Any help would be appreciated.

Thanks,
Tom Hutchinson