For anyone that owns a Blackmagic Video Assist 5″ Monitor, either the earlier one of the new 12G model, and has been looking everywhere for a monitor hood, especially for the lower brightness earlier models, here’s a solution. This might equally work with other brands.
First, get your hands on a hood for the Feelworld F570 monitor, (AliExpress has them for US$9.99), then get some firm but reasonably flexible plastic and cut it 17mm wide and the width of the monitor. Mark where the monitor 1/4″-20 holes are located and drill the holes (leave them slightly smaller so that you can thread the screws in so that they don’t fall out, I tapped mine), then apply some plastic glue primer to the hood and mounting strip and then apply the glue. Press both parts together and Bob’s your uncle (or in today’s world could be your aunt).
The final result doesn’t rattle and sits firmly in place. The plastic glue is very strong and if it were to come apart, it’s easy enough to re-glue again. It took about 20min to put it all together. And look Ma! No 3D printing monsters. This is how it came out: