Heated bed and glass clips
These clips attach to the heated bed and slightly overlap the glass. The glass I use is 8x8 inches and about 2.5mm thick. There are short and long versions of the clips. I am using four short ones and two long ones.
(Later note: I only used these for a short time. They work adequately, but less well than metal bulldog clips. Unless you use a lot of them, the glass will slip. However, I'll leave the thing up in case it's useful to anyone else.)