Synthetic bodies, or “synths,” are biorobotic androids that provide a cheaper alternative to resleeving into a human body. Synths can alternate between different "models" (appearances) depending on the individuals who inhabit them. When Lizzie Elliot was Needlecast into a synthetic body she was able to alter the synths appearance to perfectly match her birth Sleeve. If a citizen of the protectorate can't afford a new sleeve, they have the option of downloading their DHF into a synth. However, most choose not to as sleeving into a synth is physically jarring, the nerve responses are only approximations of human sensation, and things like taste and smell are severely blunted or entirely absent. The effect of frequent re-sleeving into too many synthetic bodies can result in insanity, similar to frequent re-sleeving into different human bodies. Synths are often used by sex workers and others looking for a disposable sleeve. Most of the prostitutes and strippers in Bay City and Licktown inhabit synthetic bodies for their ability to alter and augment physical attributes. Most female synths are programmed to secrete Merge5 and Merge9 to attract men.
Synthetic sleeves do not have blood. They instead have a blue liquid material inside them.