You need to practice modeling more. The screw looks very unrealistic. And hdri isnt so hard to make, just need to follow a tutorial or two. I suggest working more on stuff then submitting it, I did that when I was learning C4D too and looked like a noob everywhere I went.
Yea I know, I just like to post the very first things I do so I can get C&C on what to work on. Thanks!