Hello Naidu, after diploma in Mechanical engineering, you have various fields to proceed further, you can either take B.tech in mechanical or go for diploma post graduation courses like Mechanical Safety Engineering, Product and Design tool,etc. You can take some design course certifications like Catia, Unigraphics, CAD and search for related jobs in the area of designing. You can take either of choices on your preference.

Hope this helps.

Thank you.