bread warrior...well.. hm.. if we're talking about a collar your best bet is probably to make small slits in the lining and insert some supports.
it's not really possible to stiffen up the type of leather that is used for garments.. the method with which it is tanned... it chemically alters it so it will not react the same way as other leathers. unfortunately the only way to make it less soft is to basically ruin it, and i will not explain how to do that (it's a bad idea) ...i'd say inserting some interfacing or something between the lining and exterior leather would be the most simple solution.
shane, i've only painted on latex prosthetics, personally, so my suggestions might not be the best, but if you have no ideas you could always use liquid latex. you run the risk of losing the smooth texture if you are not careful. with liquid latex i have mixed acrylic paint in, or various other colorants... grease face paint, paint pigments, or eyeshadow. if you use liquid latex you can get it in clear and it will dry sticky, which is great for using pigment powders since it will let them stick without losing their luster (great for shiney stuff). i like searching the cheap makeup aisle at walgreens for colors since you can get a wide assortment of good metallics for very little money.
i also found this... http://www.monstermakers.com/categor...olorants.html/
which is specifically for painting on cast latex masks.. might be your best bet? if you are not in love with the colors remember you can mix things in. it looks like it is just liquid latex mixed with acrylic paint though, so you could probably do that on your own. liquid latex will be very sticky though, so again i will say it is a good idea to find an eyeshadow that will match the color you want, and some transparent powder as well (baby powder will make things look pale).
i like using small torn up sponges to apply liquid latex- you have to change them out often, otherwise you get clumpy weirdness going on. at some craft stores you can get packs of them on handles in the stenciling section.
i went to target today to help my friend pick up supplies for a group costume we're doing and while there i found the child-size bane mask. hilariously bad. it fit my head but it was awful. also smelled like the inside of a new car on a hot day.