You are not eligible for Express Entry.
You can apply for only SINP OID sub-category. (Non EE, No WES required, No Job offer required. )
Your occupation is in SINP demand list but it is regulated there. So, you have to apply for licensing and it will take about 1 year. You can still apply for SINP OID, but have to provide license before Nomination, only then you will get it. Everything is online and not very tough. Both process run parallel. Otherwise also, Nomination process takes 6-10 months. So, it is easily manageable.
Here is your NOC with licensing authority details.
2132 Mechanical engineers
Provide documentation from the
Association of Professional Engineers and Geoscientists of Saskatchewan (APEGS) showing your Engineer-in-Training membership; or you have received an academic assessment result letter from APEGS indicating that you have been assigned Confirmatory Exams.