Dear sir
I have done similar backpack design and you can check it from here
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I am a product/industrial designer engineer with 5 years experience in mechanical design,CAD/CAM design, product design, 3D modeling,3D rendering, 3D printing, prototyping and industrial design. I am using Autocad, 3ds Max and Solidworks and i can give you the quality of a company with price of freelancer and in the time.
here is a sample of my work and there is more available
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https://www.freelancer.com/u/engmahmoudsayed.html
Kindly note that this is not an exact estimation of price and delivery time. You can add me on skype to talk more about your project hope to hear from you soon
best regards