This is a hotend holder for Rostock printer with 4mm OD bowden tube clamp. It fits J-Head hotends (and other hotends with 16mm OD). It uses M3 screws instead of M4 to mount to the platform.Print without support material. There's a thin celling in the hotend hole that needs to be cut through to open the squeeze gap and bowden hole.Use 2x M3x16 (or 20) bolts + nuts to secure the hotend and another 2x M3x20 bolts to mount to the platform.You will need to point a small fan at the hotend body so that the heat from the hotend doesn't soften the mount.