Behind the scenes
The Piper Maru's name is presumably a reference to the titular ship from the 1996 The X-Files episode of the same name, which was itself named after lead actress Gillian Anderson's daughter, Piper Maru Anderson. The name Maru is particularly apt, as it means "ship" in Japanese and is commonly used when naming Japanese vessels. The name is also similar (likely unintentionally) to Shinyo Maru, the name of the ship that rediscovered the derelict on LV-426, as mentioned in Aliens: Colonial Marines Technical Manual.
The ship in the film was not real, but was portrayed by a fifteen foot long miniature, including for shots of it cutting through the Antarctic sea ice, which was made of polystyrene. Only one small section of the ship's exterior was built to full scale, for the scene where Miller and Sebastian convince Lex to stay with the expedition. This section of deck was linked to an interior section containing corridors and cabins for each of the main characters. The large hold where the expedition members first meet Weyland was a separate set. The hold walls were not actually built especially, but were in fact the exterior walls of the sound stage in Prague where the film was shot, dressed with bulkheads and painted to disguise their true nature.