Manufacturing usually requires a large fixed investment upfront and the only way for the investor to get their money back is through high volumes of production through the facility. You need to communicate in real terms that you have soft or firm commitments in hand for throughput / production that will go through the manufacturing facility. Otherwise, you will find it difficult to attract an investment. If you can get past this important toll-gate in your business model, then you can approach those investors known to invest in manufacturing. You can start by doing a Google search to list them out such as: https://signal.nfx.com/investor-lists/top-manufacturing-seed-investors | http://www.invstor.com/find-investors-k/industrial_manufacturing | I would then narrow your list down to those in India given your location. Good luck.