Unfortunately I have no advice for your visor problems. My ODST and Project Mini Chief are my Halo builds. Since I am building from the ground up, I have not made a helmet before thus having no experience in making a visor. Plus I am in a similar position in that I am trying to figure out how to make and get that iconic shape in the ODST visor with the material that I have.
The motorcycle visor looks cool and all but, from the way the pic looks, it doesn't quite fit the right way. IMO it makes the bucket look more like the Air Assault.
Have your considered using a hard hat liner to help keep your noggin in the center of you helmet?
Or you can maybe use what this guy is doing.
This is prob what I'm going to do.
I like what you did with your thigh plates.
Still need to do that with my build as well. I had all the bit cut and ready but, I had to make an adjustment and now they done fit. I have to make new ones.
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Are you still planning on doing the camo patterns on your arms and shins?
Your helmet and chest are looking good. There is something about dropping paint your armour and it just starts to bring it to life.
I am excited to see this all done and your wearing it with pride.
Sorry I wasn't much help on the visor issue. Hopefully someone more experienced will chime in and give you some good advice.