Here is Naeve using the device to melt copper!
Here is Naeve's diagram of a solar wheelbarrow, which holds the troughs in proper alignment.
Ambjörn Naeve made a great breakthrough back in the 1970s when he discovered and worked on these concepts. http://kmr.nada.kth.se/wiki/Main/PointFocus is his story of the discovery and how he tried to spread the knowelege.
Unfortunately, the Naeve Cross does not share one of the main advantages of simple trough cookers, their tolerance of movements of the sun parallel to the length of the trough. This can allow a trough cooker to work for hours every day without any need for tracking the sun. But movement of the sun parallel to the length of one trough of a Naeve Cross is perpendicular to the length of the other, so the Naeve Cross has to be moved continuously or frequently to track the sun, like a paraboloid.