If the pouch gusset bag you're using has a pre-punched slot, remember to allow for more space along the side of the slot.Thickness. Laminating pouches come in four main thicknesses: 3mil, 5mil, 7mil, and 10mil. The thickness of the pouch you use depends on your laminator because not all machines are capable of handling 7mil and 10mil pouches. However, if your laminator can handle all four of these thicknesses, then your choice of pouch depends on how much rigidity and protection you need for your project.