Cartridge loops would take more time than a block of foam, but would increase the appeal and overall quality of your case. And like many tasks, once you learn how to make cartridge loops it will become easier and less time consuming. Not in hurry I can sew 25 loops in an hour pulling that long piece of thread through. 5 to 8 loops would be relatively fast once you are accustomed to the process. Do some research on cartridge loop making, and give it a try, even if it doesn't get used in your project you will have a new skill that will make you money in future projects!