At this point, does it need that residual variation or is this just adding noise? Also, a shape inside a shape inside a shape inside a shape isn't anything anyone is likely to parse – how many bits of information is this? So maybe just go with a simple default wrench icon for all of them?
(In my experience, if an interface elements raises questions, even more so, if these are fundamental questions, you do have a problem. If not for other reasons, just for the few more bits of awareness spent on these questions, every time you see them.)
If your icon loses to a yellow cube, it is not a good icon.
And for the overall style, these kinda look like taken from pling.com where people share their packages of customized icons that try to mimic MacOS "squircle" style on Linux