BMW 5 Series (E39) Outer Windshield Cowl Covers Part Number: 51718193201, 51718193202

The objects in your image are the Outer Windshield Cowl Covers for a BMW 5 Series (E39), manufactured between 1995 and 2003. These parts are often referred to as corner "reziaki" (rubbers) or water deflectors in automotive communities

Part Details
These components are sold as a pair for the driver and passenger sides:
Left (Driver) Side Part Number: 51718193201.
Right (Passenger) Side Part Number: 51718193202.

Function and Replacement
These covers seal the area where the windshield meets the hood and fender, preventing water and debris from entering the cowl area. Over time, the original rubber can degrade and fall apart, as shown in the top part of your image.

Materials: Typically made of high-quality, wear-resistant plastic or rubber.
Installation: Designed for quick and easy installation as direct replacement parts.
Availability: Genuine OEM parts can be found through retailers like Pelican Parts or Turner Motorsport.

For 3D printing replacement automotive seals like the BMW E39 cowl covers shown in your image, TPU (Thermoplastic Polyurethane) is the ideal material due to its rubber-like flexibility, chemical resistance to oils, and high UV stability.

Recommended TPU Print Settings
To achieve a durable, water-tight seal that mimics the original rubber, use these optimized settings:
Temperature:
Nozzle: 225°C – 250°C (Start at 230°C; higher temps improve layer bonding for better waterproofing).
Bed: 40°C – 60°C. A clean PEI sheet or glass with a glue stick is recommended for adhesion.
Speed:
Print Speed: 20 – 40 mm/s. TPU must be printed slowly to prevent the flexible filament from buckling or jamming in the extruder.
First Layer: 15 – 20 mm/s for maximum "squish" and bed adhesion.
Retraction:
Distance: 0.5 – 2.0 mm (or disabled entirely). Excessive retraction often causes clogs with flexible materials.
Structure for Seals:
Walls (Perimeters): Use 3 to 5 walls. Thicker walls provide more strength and a better water barrier than high infill.
Infill: 20% – 50% for general flex. For a solid gasket feel, use 100% infill with a concentric pattern to ensure there are no internal gaps where water can seep through.
Cooling: Keep the fan low (20% – 40%) or off for the first few layers to prevent warping and ensure the layers fuse strongly.
Critical Tips for Automotive Parts
Dry the Filament: TPU is highly hygroscopic (absorbs moisture). Dry it at 50°C for 6+ hours before printing to avoid "spiderweb" stringing and bubbles.
Direct Drive is Best: A direct drive extruder is strongly recommended. If you have a Bowden tube setup, you must print even slower (approx. 15-20 mm/s) to avoid jams.
Print Orientation: Lay the part as flat as possible on the bed to maximize the surface area for the seal and improve structural strength.