NEOPRENE RUBBER

Creature Cast Rubber offers a great description of the product:

There are a few sources. My personal preference for the level of flexibility is the Chicago Latex #521.

One of my colleagues who works in neoprene all the time uses a custom mix from Critical Coatings that is very rigid (more than I like). I tried the Critical Coatings semi-rigid, and it was softer than I wanted. However, David (the owner) was very responsive to my communications and sent me some hardener to add to the liquid. I think David will send you some sample discs so you can see what you prefer.

CreatureCast Rubber offers black, which is a nice option. Their rigid formula was too hard for my tastes. I have not yet tried their other flexibility levels.

STRAPS, BUCKLES AND RIVETS, ETC.

Straps:

page2image9797456003/4″ black elastic. I get it in bulk at Amazon

Buckles: https://www.strapworks.com/34-inch-plastic-strap-adjuster

page2image979746208

Rivets: Wide double cap rivets, size small. I use the gunmetal color.

I get these from Tandy Leather.