Good work. As it's completely custom, next i'd think of making it "active mount", as in with cable fixed in it, so that you can slip phone in mount and no need for extra cable attachment step. And if you want to make it as product to sale, i'd think of means to make it universal. Easiest way to me looks like making it "flat plate" with some holes, so that wide range of Brodit phone-side parts can be bolted to your custom vent mount part & selling via ft86sf
