I wouldn't use 3mm between tow posts, 6mm would be fine, or Alumacorr, but not an ACM material like MaxMetal. Also, I'm pretty sure Grimco's U brackets are for 1/4" material, not 1/8", so you may have to bend them slightly to get them to fit.
thanks everyone, i think im gonna build a a frame for this one!!Have you considered fabricating a nice metal frame? You can use 3mm dibond with this, make sure there's tabs.
Here's one we have.