I started off with a flat plate of carbon I had left over from another project and just made up an S shaped bracket out of raw carbon which I then bonded onto the back of the flat plate.
It utilises just one attachment point which is already on the aircraft, the top panel fixture screw.
I thought it may wobble about too much with vibration but once flying it is absolutely steady.
The sequence card is held in place by 4 small bulldog clips - I also use two small pieces of duct tape in the centres but this is not really necessary.
A 'mark two' version of this would have a hinge on the bracket so you could raise up the holder to see the EFIS but for now I am happy to forgo seeing the EFIS for these short flights.