I have an untested (not even populated yet) blank board that I am just now turning my attention to. I'm working through this and do have a Junk Yard that I can test my board in. I do NOT have any brackets. I had asked a friend to work on 3D printing some but that was before the current situation that we're in.
https://pinside.com/pinball/forum/topic/dumbass-test-and-reproduction-pcbs/page/2#post-5579763
If you are unable to find one (or don't want to risk buying across ponds on either side of the continental US) and you're patient (while I build and test) I can provide one once I have it working.