The ribbons were finger-weaved (if that's what its called) Indian-styled. I then hot-glued it over the base (t-roll and pop bottle), folded over the sides, hotguing them in place, and folded the ends in, trimming the excess.
This picture shows what I did for the inside. It looked rather messy b/c the weave wasn't thick enough to cover the entirety of the inside, lol. So I took a piece of black ribbon and glued it in there. It covers up the "seams" rather nicely.
The toilet paper roll was my base. I cut a line in the toilet paper roll, going straight up, then cut out two bands of the same length. Because one wasn't thick enough to cover my wrist, I overlapped them together when I hotglued. Then I cut a [20 ounce, but the litter ones would work better] Pepsi bottle the same way I did the t-roll, after cutting off the tops and bottoms. I cut two bands from it and before hotgluing them to the t-roll, one on top, one on bottom, I put it on my wrist so that the glue would form to my wrist. Otherwise, it would make a circle and be rather uncomfortable to wear, in my opinion. The t-roll is for a base; it adds thickness and some stablitiy. The pop bottle is for more stability and it keeps the bracelet round-ish. Cardboard would flatten after a bit of abuse. Try to keep the plastic and cardboard the exact same length when curved. Otherwise, it'll look funky. Also note that you don't want to be cutting the "base" after its all glued together b/c the hotglue comes apart quite easily. Trust me, its not fun to peel hotglue off cardboard so you can reglue it. A tip: before putting on the ribbon, or fabric if you choose, put some batting down. This will make the bracelet look less cubic. I didn't have any handy, nor did I think of using some, when I made this bracelet, but I know I will the next time I try.
Glad you like it; I'm rather proud of it myself.