Best thing to use

[Dhos1]

I’m trying to make some cuts in the fender well from inside and under the hood of the car. Trying to make some small access holes for some stuff, what’s the best thing that you have used. I tried a dremel but I will be there all day. Take a look at the picture below. For reference tgat is the driver side of the car next to the washer fluid bottle.

 

[1986 Buick GX1]

Would a hole saw work? Or maybe a unibit/ step bit?
Maybe you want a square hole, drywall saw?

 

[Dhos1]

I’m looking at a few things because the metal layers there are pretty tough

 

[BigboostGN]