When it comes to blinders I've tried a bunch! I shoot with oakley glasses, and nothing seemed to work. Two years ago I shot the Bianchi Cup, and lo and behold I see Doug Koenig walking around with blinders cut out of an ammo box. He ends up winning the cup that year.
The following season I pulled out an ammo box, and started experimenting with different sizes. I have been using them ever since, and when they wear out, just pull out another ammo box and make some new ones. They might not be pretty, but they work! It's not like we are out there for a beauty contest, just need something to keep the glare out. And trust me, I am not winning any beauty contests!! I am a fair to middlin' shooter, and since I started wearing the blinders my scores have become more consistent. If you don't want to use ammo boxes, I have some team mates that have made them out of plastic school binders.