This is the CD Box that I used.
You will use the groove on the inside of the CD box and of course you need an embossing tool.
Place the card right-side facing down as in the picture, holding it tight. Start embossing the line..
........ slowly and lightly at first until you find the groove ... embossing down til the end.
When you do all the line you can go back up and down for a second or third time until the line is raised enough.
Repeat this for all sides.
Hope you like it and find it useful.
Thank you for looking today.
Wishing you a lovely Sunday