OnePlus 7 phone mount with expanding clamps

I recently bought an MX-5 NB which had an aftermarket stereo with a pocket beneath it. So when looking to mount my mobile phone I wanted to try using that as a mount point So I designed a simple expanding clamp fixture, with a bottom plate, top plate 4 parrallel arms and using bamboo skewers for pivot pins. with a expansion spring of the right length held between two of the pivot pins on the diagonal , you can expand the spring by pushing the two plates over, slide it into the pocket whilst co