So I am thinking of trying to make armor out of 1/2" camp mat and then wrapping it in leather and using pop rivets to hold it together. I know this is a question for my chapters marshals but would this be an acceptable 1 point armor.
I don't know if I'm picturing your design quite right, but it would probably be acceptable armor, largely on account of the leather on the outside. Even thin garment leather counts for 1 point. If you're doing the leather work anyway, though, I'd suggest just making some leather armor. Foam armor tends to look a lot like foam armor unless it's done really well and, assuming I'm picturing your idea right, I feel like there are some structural issues with your design. I don't really see it holding up to motion or combat for very long.
When you say pop rivet, I assume you mean something like this. I can see any rivets ripping/stretching through the foam really quickly, and pop rivets are really meant for sheet metal and other rigid materials. I don't even know if you can set them through something as thick and soft as foam - the mandrel head needs something to pull against to get the tension that actually sets it. If you do decide to use pop rivets (and they work), I wouldn't use them on any joint that's intended to move around a whole lot, and you want some tight-fitting washers on each side or the rivet will just pull straight through the first time anything pulls on the foam. Chicago screws or rapid rivets might work a little better, but you'd have to find some with a long shank to go through 1/2" foam.
It looks like you'll be playing at SoMN - depending on sizing, I can probably bring some loaner armor for your first game and drop off some scrap leather while I'm at it. I have a tub of old leather scraps I don't really have any use for.
Ah, my stuff is built more around the 5'10" size large sorta area. I can still bring some of my leather scraps and some accessory pieces (bracers and a chainmail coif) even though I don't have a main chest piece that would fit you.