~~~ MOLD DESIGN [as defined in a "Guide To Collecting Gaming Checks And Chips" by Howdy Herz]:

1- MOLD: The pattern or design that has been "MOLDED" into the surface of the check [chip] during manufacturing.

2- MOLD DESIGNS [ALL KNOWN "DESIGNS" are/were illustrated in Herz' work]: There isn't any illustration, nor is there any clay composition chip drawing showing/explaining a "PLAIN" mold w/ a die-cut or HS inlay except under PIMC chips...

Further into descriptions two C&S chips are illustrated with notes: "A plain clay check [chip] with an inlay was offered by various distributors as a 'crest & seal' check. These do not have a "mold design" but are a composition checks."

...and below the C&S illustrations are DIE-CUT Metal Inlay chips; one w/o any mold design and w/o any mention of the term PLAIN to describe/illustrate a mold deign, of which there is none... and there are no other terms describing chips w/o a "mold design" except for the section that illustrates 'actual' distributor catalog pages with printed decriptions -- and the chip types you illustrate in your post are described on several pages as "INLAID" and nothing more; one distributors' page, onward; with no mention of the term PLAIN MOLD, anywhere, though a MOLD DESIGN is mentioned when a "DIE-CUT" inlay with such designs similar to and common w/ other die-cut inlaids where the MOLD DESIGN is mentioned (see page B-16; Hunt & C0. No. B203).

After Herz' work, other authors/catalogers have described C&S casino chips under MOLD as being "PLAIN."

So, I believe if you need to describe a MOLD (even though there isn't any) while illustrating your chips (or any die-cut INLAID chip without a MOLD DESIGN), you would be safe with the term PLAIN since there are DIE-CUT INLAID inlays such as you illustrate on chips with a MOLD DESIGN.

I would also like to mention that a complete chip; of any type manufacture, has also been known as a 'MOULD' in our hobby.