  The increased adoption of additive manufacturing (AM) and the acceptance of
AM outsourcing created an ecosystem in which the sending and receiving of
digital designs by different actors became normal. It has recently been shown
that the STL design files -- most commonly used in AM -- contain steganographic
channels. Such channels can allow additional data to be embedded within the STL
files without changing the printed model. These factors create a threat of
misusing the design files as a covert communication channel to either
exfiltrate stolen sensitive digital data from organizations or infiltrate
malicious software into a secure environment. This paper addresses this
security threat by designing and evaluating a \emph{sanitizer} that erases
hidden content where steganographic channels might exist. The proposed
sanitizer takes into account a set of specific constraints imposed by the
application domain, such as not affecting the ability to manufacture part of
the required quality using the sanitized design.
