I cut up the wonderful T Brace by Electrico so that it would work on the bottom right of the frame. The T Brace worked so well ... why fight a good thing? I could have done a nice rounded corner, but I kept it minimal. I added a small wall to the bottom side so the gap wouldn't be so visible.
It's possible to print standing like it is or on its flat side (with supports everywhere). I chose to print on its flat side with supports everywhere. As one of the pictures shows - I left a very thin layer of support material behind for the tightest fit possible.
Important note: My Anet A8 has the paper still on the acrylic frame, and this fit snug. Since I cannot test this on an Anet A8 without paper, it might need adjusting for a paperless acrylic frame.
See other side:
See upper braces by Electrico:
Whatever settings you used to print Electrico's T Brace can be used here.