I have created templates for two diamond fold cards with a finished size of 100mm (4 inches) when folded flat. Template 1 has diamond size of 100mm (4 inches). Template 2 has more folds and a diamond size of 70mm (2¾ inches). Both templates would be easy to scale up as required.
I have used template 1 with the PinBroidery MM-4 Mini Tulips Pattern. It is stitched on white card and mounted on the diamond fold card with sticky fixers.