Finished this a while ago, but haven't had the chance to post pics until now. The first photo was Instagrammed, so the color is a bit darker. Used Duplicolor Metalcast red and blue. Made the brackets, straps, and star on my own (based on Valor's tutorials) and got the data plate from Brotherfoster.
For the detachable straps, I ended up using 3M's high strength velcro to attach the straps to the brackets (types 250 and 400, it's a stronger bond if you combine the two different velcros). Man, that stuff is strong. The shield is in no risk of dropping off and it takes quite a bit of strength to pull the straps free. All in all, I was pretty pleased with the way the strapped worked. One downside:
On their own, the straps themselves did't quite make it all the way over my shoulders. You could wear the shield like that, but you'd need to maintain a constant effort to make sure it stayed on. To remedy that, I ended up making another strap to go across my chest and pull the shoulder straps taut. The additional strap connects to the hinges using the same velcro that attaches them to the brackets.
I still don't have 100% range of movement in my shoulders with the shield on (can't reach across my chest), but it feels relatively comfortable. If I could do it over, I'd probably move the brackets inwards by about one inch on each side. That would give you more freedom of movement around your shoulders. Oh well.
In any case, I'm super happy with the shield. It's certainly not perfect, but I know I made it, so that's really satisfying. Special thanks to Valor, GF, Brotherfoster and the many others on these boards who helped me with this project!