I'm going to use one of those adhesive backed magnets they use to put business cards onto. I'll just use the adhesive side to stick one down to 2 1/4" and leave it there. It's thick enough that I can easily use it as a guide (I can always lay a few more on top when it's in use). But, it'll be thin enough, it won't effect anything else that I'm sewing cause the fabric will just go over the top of it.