They are 3D printed using TPU, a very strong, soft plastic that is perfect for holding wires in place. Use CA, epoxy, Duco Cement, or double-sided tape to glue in place, or a 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.