feel free for further questions
first make a "wall" like this one
then make a layer that touches the wall and take the angel tool to make an angel in this case 35°
3rd step: delete the layer that only the line that touches the wall is left then draw a curved line to the streigt and
make the same under or over the existing "profile" of the hill
next step drag the surface to the required width
then erase the upper surface that only the bottom and side walls are left
last step: you can make it any texures or colours you want
so and that was a quick tutorial how to make a ski jumping hill sketchup
sorry for my english
)
I would prefer the video
