A few years back, I built a DIY field monitor project that I found on Instructables (http://www.instructables.com/id/Affordable-external-monitor-EVF-for-DSLR/).  The screen for the monitor is an LCD made for use with an automotive back-up camera (http://a.co/2DpSYy2).

The original project called for mounting the Monitor to the camera using a cell phone clamp, but the the cell phone clamp doesn't include a hood (which makes the screen much easier to see when used in the day-light).

The 'lug' at the bottom of the frame has a 1/4-20 threaded insert epoxied into it.  The threaded insert is metal, allowing for stronger threads than if the plastic were simply threaded. The pilot hole for the threaded insert was drilled by hand -  not really the best option as it takes a lot of epoxy to fill the void and hold the insert in place - but it does allow some flexibility with regards to the insert you choose to use.

As you can see, the monitor is held into the frame with a simple rubber band.