A device for providing a lockable modular connection between two parts, the device includes a first element for connecting to one of the parts and a second element for connecting to the other part. The first element includes a rod secured to a ball joint. The second element includes a housing containing the ball joint. The device has an inner space between an inner face of the housing and a peripheral face of the ball joint, and a locking element arranged between the housing and the ball joint. Motifs are arranged on the peripheral face of the ball joint and/or on the inner face of the housing. The locking element consists of a hardened material that fills the entire inner space and with regard to which the motifs form abutments in order to hold the ball joint in a fixed position in the housing.