Arduino USB triggers for dslr cameras (multi-camera trigger system)

I am designing a custom 3D scanning rig that uses multiple cameras (12 in total) to capture images from various angle and view all simultaneously. See this short video for example. [login to view URL] The camera model is Nikon D5200. There will be 12 of these cameras. Each one of them is connected through a USB cable to a PC / laptop. We use digicamcontrol open-source software to control the camera. Triggering the cameras using the software and simple USB cable set up comes with a delay between each camera and is not ideal. We want all the cameras to fire simultaneously, hence taking 12 pictures of the subject in all directions at the same time. We need an arduino / USB relay for triggering all the cameras at the same time. See this link for example. [login to view URL] There is also some discussion about this topic here [login to view URL] Our system requirement is as follows: A) 12 cameras B) all connected to the PC via USB cable C) Needs to trigger simultaneously. We have got the first two parts sorted, at the moment we are trigger them via Transceivers (Yong Nuo) and they are not ideal because each one of them needs 2 AAA batteries and we can't afford to keep checking and changing batteries. The system will be running continously for at least 14 months. You job is to design and create an Arduino/ USB relay that would allow simultaneous trigger of the cameras. Budget is NZD 250 for your hours and an additional NZD 250 for the electronic components that you need. We will cover the shipping cost if you are based overseas. Please apply with the word beginning with "3D SCAN". That is to ensure that you have read the proposal and not just apply blindly. Thank you again for reading.