Here is an svg template for cutting a box to hold A2 cards and envelopes. The original design for this came from here. Set the height at 7.5 inches for A2 envelopes. I did not put the score lines in the svg file. Score at the dashed lines shown below.
These files are for personal use only. Feel free to link to this post, but the files are not to be shared or distributed in any way.
Download the files from here.
http://www.mediafire.com/file/nxxzzn0ww0w/card box template.svg