These came out in special packs a while ago, I guess they are rare Lego collectables.
C-3PO is a protocol droid built from spare parts by nine-year-old Anakin Skywalker. The droid’s was a secret, as Anakin didn’t want him taken away by his master, Watto. The number 3 in the droid’s name was Anakin’s stab to show that the droid would be the third member of his family, beside himself and his mum. According to A Guide to the Star Wars Universe, C-3PO was activated around 95 PE. By the time Anakin was freed from slavery by Qui-Gon Jinn, C-3PO was nearly completed. All he had missing was an outer skin and some small modifications. Eventually, C-3PO was given a gold outer skin like we see in the movies and was reunited with the astromech droid named R2-D2 years before the Battle of Yavin.
The two had many escapades dodging Olag Greck in the Kalarba System. C3PO was the victim of tampering by Movo Brattakin, who inserted an initiative submodule in his leg to help expose Greck and Jace Forno on Boonda the Hutt's moon. After these adventures, C-3PO was ultimately assigned to use in the Imperial Senate, translating the proceedings for a number of alien diplomats. It was during this time that he became "friends" with R2-D2, one of the Navy's astromech droids. Even though they had separate functions and programming, they maintained their version of friendship. Note that, despite what the Droids comics say about their meeting, the Star Wars Radio Drama infers that C-3PO and R2-D2 didn't meet until C-3PO was assigned as R2-D2's translator during routine labour assigning on the Tantive IV. When the Senator Palpatine began to gain his power, the growing Alliance took Threepio under their domain and assigned him to mediate the various agreements between the Alliance and alien worlds. One such mission led him onto the Tantive IV, where he was tagging along with R2-D2 one too many times.
When Artoo escaped from the ship in an escape pod, Threepio followed him, fearing that the Empire would only melt him down. Since then, he has been owned by Luke Skywalker following his auction at the hands of one of Tatooine's roving Jawa clans. Luke is C-3PO's 43rd master, having been owned by diplomats and starshipwrights before then. He has helped Luke whenever possible, and has also maintained his friendship with Artoo, although just like old friends they constantly bicker at each other. C-3PO was portrayed by Anthony Daniels in all three Star Wars films as well as for both Star Wars radio dramas on National Public Radio.