Dave Corkrum writes [141231 MMDigest]:

> I suspect they used a linoleum block which they carved and then
> inked and printed on the discs.  Later, they probably used another
> linoleum block to print the title, catalog number, and composer.

A similar option is the "polymer plate" used by letterpress printers.
It's a flexible plastic plate, usually mounted on a wood or metal base,
and it looks somewhat like a large rubber stamp.  I've used them for
printing intricate logos on paper shopping bags.

There are a couple of different versions, but usually the finished
polymer plate is made by exposing the raw material through a negative,
washing out the unexposed parts, and re-exposing to harden the whole
thing.  You can do this in your workshop or there are services
that will make the plates for you.  A Google search for "photopolymer
plates for letterpress" will return lots of info, and you can even buy
scraps of the material from boxcarpress.com.

Carl Zwanzig - z!