I tried to do an helmet myself last weekend. I had a bicycle helmet and a construction helmet. I feel that even with light components and a webcam the helmet tend to pull from the front. That's why many put a weight in the back. But I decided that's it's not worth it, it is to heavy for a serious actor.
For now, I will stick to the standalone webcam in front of the actor. The tracking is quite good even if they move a bit and this will be a much better experience for them. On top of that my audio recording booth wasn't build for body motion capture, so I prefer to do it as a second step process.
Directing the actor to have the voice you are looking for and capturing the facial motion capture simultaneously is already great for me.
Eventually, I will buy a real facial mocap helmet.
Ryzen R9 5950x, RTX 3090, 128Gb Ram ,2 x 2 TB Samsung 980 Pro M.2 SSD
Horror Stories in VR
Immersive Sound VR
Immersive Sound VR on Oculus TV