The Regeneration Cradle is a medical device that can heal wounds by grafting a simulacrum of organic tissue to the patient and having it bond to the patient's cells. Thus, it can also be used to create synthetic tissue.
Shortly after Ultron obtained a cache of Vibranium for his plans, he, Quicksilver, and Scarlet Witch coerced Helen Cho to use her Regeneration Cradle and the Vibranium to construct a new, more powerful body for Ultron. Though Helen Cho said that the Cradle could not create a functioning body, Ultron disagreed and stated she merely lacked the proper tools. Ultron used the Scepter to control Cho and began work to create a body.
The process to bond the Cradle's printed tissue to the Vibranium was a success and Ultron integrated the Mind Stone into the android body. Yet before Ultron could transfer his consciousness into the new body, the Maximoff twins (Scarlet Witch and Quicksilver) betrayed Ultron and had Scarlet Witch secretly undo Helen Cho's mind control. Helen Cho then proceeded to stop the upload process and was later shot while the Maximoff twins escaped. Though Ultron tried to finish the upload process in a mobile truck he had confiscated, the Avengers tracked him down, interfered, and took the Regeneration Cradle; forcing Ultron to return to creating bodies out of Vibranium as a substitute for his plans.
The Regeneration Cradle was taken back to the Avengers Tower, where the Tony Stark convinced Bruce Banner to help him put J.A.R.V.I.S.' protocols into the android so that they could create an ally against Ultron. Captain America and the Maximoff twins stood in opposition to that plan and had a scuffle with the Avengers at the tower. The Regeneration Cradle was deprived of power as a result of the scuffle's damage, causing the android to almost die. In the end, Thor managed to save the android by using his lightning to power the Cradle. The Regeneration Cradle then exploded and the android, who later referred to himself as Vision, leaped out of the destroyed chamber, confused and hostile. After the Vision calms himself, the Vision joins forces with the Avengers in the fight against Ultron.