remove using extrude

I am working on a project - Designing a racecar (LMDh category if curious). Problem/Question: I am trying to cut into the [insert correct terminology here] but in a way that it cuts more evenly into the extrude, rather than simply cutting it from one direction. I'd like to make that space for curved headlights + an extra…

I am trying to create a hole at this place for a while, but I am not able to create a plane at that particular place to create a thorough all hole, not sure what is the best way to do this. I am pretty new to Onshape, so any help here would be useful. This is my document,…

I have a sheet metal part that I am unable to extrude-remove material from the flanges. I think OnShape is trying to tell me what is wrong but I don't get it. I have extrude-removed holes and fillets on flanges in other drawings with success but using the same process here is giving me an error this time. Work Flow: Sketch…

I was able to successfully remove the right semicircle using the extrude command but the left is a different story. Any ideas why I can't cleanly remove the left semi-circle using the extrude command?