Walmart sells magnetic tape strips in the craft section, 18 pack for around a dollar.
Seperate them into three sets 1 inch wide, and cut them into half so they are now 2 inch long. Attach them together, making sure the magnets match up, then peel and stick them together, thick as you need. Dont peel off the top one.
The strips are scored but not seperated, so you can seperate them into 1 inch wide strips instead of 1/2 inch wide ones.
Makes 6 or 4 guides depending on thickness.
Oh.. dont use these on an electronic machine! :)