The medieval Catholic Church was the primary institution concerned with sexual transgressions in Europe. That’s why the primary sources of information on sex toy usage from the middle ages are penitential manuals and trial records. While penitential manuals listed what was prohibited, trial records documented what people were actually accused of.
First to be clear, the definition of sodomy today is anal or oral sex, but in the past its definition was much more broad and encompassed anything deemed "unnatural penetration” which was anything other that male penis inside a female vagina.
In the late 13th century, Bertolina of Bologna, Italy, along with some other women, was tried for sodomy. An anonymous accuser testified to her public reputation as a sodomite and claimed she had used a dildo with two silk testicles to satisfy her female lovers.
Another famous case is that of Katherina Hetzeldorfer of Speyer. In 1477 she was accused of creating a male member out of leather, cotton, and wood. Her creation was perfect for committing what was called in this case: “carnal offenses with another woman or roguery.” While this seems like the standard stuff we’ve seen alluded to before, Katherina’s must have been a very talented engineer, as her appendage could be used to urinate out of and could become erect when in use or lie flaccid when not in use.