Does anyone know where I can get some custom slings sewn? I'm looking for someplace I can have slings bartacked to custom lengths for climbing runners. I'm mainly looking for a shop in the US or Canada.

I haven't been able to find 9/16" supertape slings and thought I'd buy a spool and have some sewn.

try

www.fishproducts.com
or
www.yatesgear.com

I believe both can do custom length slings, but Russ may offer the most 'custom' services.

Mtntools in California also also does custom runners and slings, I think they can use supertape or ultratape. You might want to check them out (http://www.mtntools.com/index.html ) look under services, I think they also offer a discount when buying runners and biners together! Good luck