how about doing master in mechanical designing after mechanical engineering ?

Good idea. You will have sufficient scope to get rise in your career in India nad even outside.

The subject of M.Tech. specialization is Machine design and it is offered by all the A-grade engineering colleges. its a good subject to pursue and employability will be good in automobile, casting and fabrication industry. Apart from that HAL, Railways, DMRC, ISRO and shipping industry also require

Dear Nazish, Certainly it's a better option but please check how many Indian universities are offering this programme.

diploma comlete after B.tech addamisation