Making slopes on a window in a garage

We completed the finishing of window slopes in the garage (Sandpit). Initially, the slopes looked unappealing, so we decided to improve their appearance.
All smooth surfaces were primed with quartz primer to ensure strong adhesion (visible in the photos and videos). The windowsill was then secured to the prepared surface. Using boards, we created slopes of equal width and shape.
Irregularities at the junctions and on the slopes themselves were carefully filled to achieve a smooth surface. After cleaning, plastic corner pieces ("angle bits") were attached with silicone for added durability. No painting was done, as this is a garage space.

Slopes on the window

Sandpit