IMHO My guess is that they WERE made by hand. On page 125 & 126 in Dale Seymour's AGC, several Horseshoe Ivory chips are shown. Ivory chip designs were "hand scribed" or scrimshaw. See also page 19 on transitional chips. The first edition AGC has the approximate dates and chips of this type are dated 1880. Clay composite was introduced in 1880 and my guess is that some of the Ivory craftsmen made these before the engraved process was perfected. Just my humble opinion. It would be nice to hear from other antique clay or Ivory collectors on this.