A roboticist was an engineer who designed droids. Morgan Katarn, a leader within the Alliance to Restore the Republic, became a roboticist through self-study and designed his own multi-purpose droid, WeeGee.
A qualified roboticist was be able to install parts of a droid to another and fine tune them; when 8t88 lost his arm, he retreated to Sulon, and a new arm from another 88 unit was transferred to him; lacking an available roboticist, the droid installed it himself.