S.D. Codified Laws § 44-15-4
If a customer does not respond in person or by mail to claim possession of the particular die, mold, form, or pattern within ninety days following the date the notice was sent, or does not make other contractual arrangements with the manufacturer for storage of the die, mold, form, or pattern, all rights and title of the customer, except patents and copyrights, shall transfer to the manufacturer. The manufacturer may then destroy or otherwise dispose of the particular die, mold, form, or pattern as the manufacturer's own property without any liability to the customer.
This section may not be construed in any manner to affect any right of the customer under federal patent or copyright law or federal law pertaining to unfair competition.
SDCL 44-15-4