Longarm rulers are either 1/4" or 3/8", never 1/2". (The rulers we use with the rotary cutter are thinner than 1/4".) 1/4" is fine for most longarms, but you should check to see if they work with your hopping foot. There is an excellent class on craftsy by Kimmy Bruner on using your ruler for quilting. It's really slanted toward people using a longarm (or midarm) rather than a DSM, but the lessons are supposed to apply to all kinds of quilting from a design standpoint. I took the class and highly recommend it. For ruler work on a longarm, you do hold the ruler with one hand while you move the machine with the other. Adding a suction cup is totally unnecessary IMHO.