ACM channel molding

[Billct2]

I'm doing a 100' storefront with matte black 3mm ACM. I was wondering if there is a nice aluminum "H" channel to use on the seams instead of just butting them together.
I checked Outwater Plastics but I don't see one for 3mm(1/8")
Anyone have a source?
Thanks

 

[J Hill Designs]

http://www.gordonglassusa.com/group/4901/CRL-1-8-H-Channel.htm

 

[Billct2]

Thanks