You can get the Link Material from Steve at PBR (http://www.pbresource.com/tools.html)
From there web page;
"Did you ever run accros a broken Flipper or Slingshot link and did not have one in your tool box to replace it? Do you have an unusual Flipper Link that no vendor offers? We are offering the Link material so you can make your own!
This is sold in a strip: 7/8” Wide by 12” Long by 0.093 Thick(3/32”) and cost $1.25"