The 3DO Protocol/Service Droid was an ancient series of protocol and service droids that was manufactured by Duwani Mechanical Products around 4000 BBY.

The 3DOs were humanoid in form and equipped with the top of the line circuitry and servos that were needed for repair tasks and other detailed work. Its visual and auditory sensors were capable of seeing in the Human range of vision and processing Human levels of hearing; it was also built with a vocabulator capable of mimicking Human speech. Like most droids built in that era, the 3DO series required frequent recharging and maintenance.

A-3DO, the protocol droid belonging to Andur and Nomi Sunrider, was a member of this model series. Andur paid 1,500 credits for A-3DO who, however, was not new at the time of sale.