Can you do the procees from h1b to EB3 with the same company by yourself?

Has anyone done the process from h1b to EB3 by yourslef ? I want to see if I could avoid the 7000 dll attorney fee. The part that I know is though is the perm with all the interviews the employer needs to do. If somebody has ever done this by themselves or know of somebody that has done it and knows its POSSIBLE please let me know.

Thank you!!!