They 3D printed using TPU very strong soft plastic perfect to hold wires in place. Use CA , epoxy, Duco Cement, or double-sided tape to glue in place or double-sided tape hole is 6mm Dia.
TPU material is a group of thermoplastic elastomers with good elasticity and resistance to stresses like abrasion and oil lubricants. Its structure consists of soft and hard segments linked together in the chain.