Dear Cristiano,
I run a management consultancy which provides end-to-end procurement solutions for a variety of businesses and industries.
Your business idea sounds very interesting and it would require a robust plan to find the right manufacturer.
Therefore the first step of the search would be the most important and laying the foundation:
1. Set the requirements, incl. volume, location etc.
2. Send out Request for quotations / interest to potential manufacturers
3. Analyse Feedback - Confirm with manufactures capabilities
4. Summary and proposal to you
Since you are looking for a long term partnership with the potential manufacturer, a potential site visit needs to be thought through. This will be dependant on the location and you might require then a third party auditor to confirm the capabilities.
If you have any further questions, you are welcome to contact me!
Kind regards,
Klaus.