I'm trying to improve my Solidworks skills, so I thought it would a good idea to fully model my drone, but I'm stuck on how to model the top case. 

I don't know how to do this kind of weird insertion on the top.

I tried doing a swept surface with a projected curved that went to the back (tangent to the surface) to the front (2/3mm down the surface), but it created a incredible small radius of curvature which didn't allowed me to thicken. 

Then I tried to knit the surfaces into a solid and projected a sketch to make like a chamfer extruded cut but it wasn't possible. 

Who would you do it?