The Emperor introduces his new assassin droid as "My own creation, M-OC". 'MOC' is an acronym used in the Lego community that does indeed stand for 'My Own Creation', indicating it was designed and built by a LEGO fan without instructions.
Mon Calamari ship builder Quarrie first appeared in Wings of the Master (2015). He is named after Star Wars concept designer Ralph McQuarrie.
The Aurebesh text visible on M-OC's viewscreen translates to "Targeting".
Quarrie's Astromech droid BG-81 is named after ILM model maker Bill George, who designed the B-Wing fighter for Return of the Jedi.