HI I am new to leatherwork to.
I have seen quite a few cuffs here that are not lined, and I don't plan on lining the pair my daughter wants me to make her.
You might try rubbing saddle soap into the back of your cuff to soften it, and there are plenty of oil or beeswax products that might help overall with softening it up a bit, but that will depend on what finish you want and if your painting the cuff or just dying it.
Also, are you wet molding your masks? because that will stiffen the leather and you shouldn't need to wet mold a cuff.
Just keep reading on this forum, there is a wealth of info here!
Natalie