Hi,
To give a very vague idea ,the minimum eligibility amongst many others is passing 10 with minimum 35% marks in aggregate with Science subjects or even more.
But I would suggest you to check out these colleges and from their official site you can cross check the minimum passing marks and other criterias,

Government Polytechnic , Mumbai
S H Jondhale Polytechn ics
V.P.M.'s Polytechnic
Vivekanand Education Society's Polytechnic
Adesh Polytechnic Colleg e
Anjuman Polytechnic
Agnel Polytechnic
Chhotu Ram Polytechnic
Adhiparasakthi Polytechnic Colleg e
MEI Polytechnic
Government Polytechnic
Ananda Marga Polytechnic
Seth Jai Parkash Polytechnic
AANM & VVRSR Polytechnic
Andhra Polytechnic
Bongaigaon Polytechnic
Bapatla Polytechnic College
Government Polytechnic College Ambikapur
Government Polytechnic - Kirodimal Polytechnic Society
Government Polytechnic Miraj
Government Women Polytechnic College
Kalinga Polytechnic Bhubaneswar
Government Womens Polytechnic
Yamuna Polytechnic for Engineering
T. B. Girwalkar Polytechnic