I have past experience of designing cases for Iphones and Oneplus 6T. Please send a message to discuss more. I also have the 3D CAD model of Iphone X so designing the case won't be an issue. The quote will vary depending what kind of case you have in mind, also 8mm thick cases are very unusual. The usual thickness goes from 3-5mm.
I am a mechanical engineer with 9+ years of industrial design experience using Solidworks in various fields like consumer products, smart wearables, automotive, electronics enclosure, collectibles design etc.
Have past experience of designing products for injection molding and 3D printing and can provide appropriate tolerances on the design.
Along with 3D CAD files, i can provide 2D CAD files and renders for marketing purposes as well. If required i can perform FEA on the casing as well to ensure it doesn't fail under load.
I have successfully completed 200+ projects on the site .
You can find my online portfolio here: https://www.freelancer.in/u/soumyasamanta12