masking window overlay 3d model

Design a masking overlay for the damaged section of the window sill or casing visible in the photo. It should completely cover the hole, gaps, cracks, and irregularities marked in green. The element should be hollow and slide over the existing section like a U-shaped cover – covering it from the top, front, and bottom. It should not be a solid block, but an aesthetically pleasing cover. External dimensions: top edge length 29 cm, bottom edge 30 cm, front height 5.5 cm, depth/thickness 3 cm. The left end should be rounded/oval, the right straight, and flush against the wall or window frame. The surface should be smooth, white or creamy white, similar to the overlay in the second photo. Slightly rounded edges. The element should serve only a masking function, not a structural one. Material: plastic or 3D print. Leave a small installation gap of 1-2 mm inside so that the element can be easily slid on and adhered with mounting glue, silicone, or tape.