T-visors can be purchased pre-shaped, or made yourself. There are many great vendors for them or you can make them yourself.
In canon mandos we typically see plain black smoked acrylic, and only one or two colored ones. We don't see visors from other properties such as hex/honeycomb pattern, etc.
A good vendor for buying them pre-made is T-Visor.com. They make smoked black acrylic visors.
March 2023 update: going out of business
A vendor for both smoked acrylic and mirrored visors is Kalevala Visors. They have a variety of colors.
Their website is here.
Their for-sale thread on the forums is here.
UPDATE: it has come to our attention that this vendor currently is very behind on orders with minimal communication and thee have been many reports of poor quality. Due to this, we no longer recommend this vendor and urge caution before proceeding with this vendor.
Welding Masks:
Many people buy a welding shield mask and cut it out themselves to fit their helmet.
More info coming soon
A great modular option is general army helmet padding. These have sticky backed Velcro pads to put on the inside of your helmet, and the pads Velcro onto them.
These on Amazon are a great option if you prefer the military modular padding. They are about $20.
You can also opt for a full helmet pad lining, there is a vendor on Facebook that makes one that looks like the inside of a mando helmet. They can be reached on their Facebook business page here. Theirs run about $35
You can use any type of foam in your helmet you have laying around. We do recommend you secure it inside your helmet (glue, Velcro, etc). Foam is better than hard material as it can squish down and is softer on your head.
More info coming soon
More info coming soon