I think the biggest problem here is that this ^ shows. It seems to me, you are just randomly sketching things without first understanding the product’s function, parts, assembly, use, etc.
I’d suggest first to do more research (I assume you’ve already done some). What are the main functional bits of the nail gun? How do those components relate to each other in space? What are the usable bits of the nail gun and how do those relate to the user?
In terms of sketching, I’d suggest first to put down the markers. They are not helping, and in fact as others have noted hurting the communication, but even more so it seems the process.
Second, I’d suggest starting with orthographic views. Side views using an underlay would likely be the best way to start to develop those relationship between parts. An old prof of mine used to say “fix in space the parts that need to be there, then connect the dots” (I’m paraphrasing, but hopefully you get the meaning).
Make your designs purposeful and have an overall theme and style. At the moment, everything feels totally random, like melty plastic parts or like a kid’s assembly of tinkertoy parts (circles, tubes, etc.). I don’t see any overall product language in the designs or any relationship of one part to another.
Once you get the above down, you can start really designing, but not until then. At that point, you can try different “styles” on as an exercise that might get you started (but not necessarily to the final solution). Try one very blobby as if Karim did it. Try one very rectilinear as if Braun did it. Try one very masculine, try one feminine, try one PoMo, try one futuristic, etc…
A great example of a similar project that involves functional parts, different components and configurations is this-
Also some great sketching and illustrates the focus on design, not wacky marker work.
Hope this helps. Would love to see some updates to view how things progress. Power tools can be very difficult as they incorporate all kinds of visual and functional semantics and features, but if done well can be a great portfolio piece.
R