Go with these pastry rings / stainless hoops. I used it on mine (Page 6 of this thread). The thing is 2"tall, and is heavy duty. Just make sure you select the right diameter from the drop down at Amazon.
Also, an update to my hopstopper, I wouldn't change anything. The hopstopper catches probably 65-70% of pellet hops, and 100% of leaf. There is just enough of a boil to cause currents in the wort inside the hopstopper. Any other size mesh and more **** would get in/out. If ANYthing, go with a thicker wire than what I have (one step up), but be sure you stir inside the hopstopper during the boil because there might not be much current. A little agitation never hurts once in a while.
You can't sew this stuff. You'll get bloody trying and it isn't worth it. Just fold over every rough edge (trust me) to give support, and then rivet there. Note though those folded spots have a higher tendency to collect crap. Mine is definitely seasoned from all the hops it has seen, but I appreciate that effect. I still get it 95% clean after each use.
Brewed some DFH 60m IPA on it twice now, the utilization is great. Cleanup is easier.