Bear in mind that silicone and latex don't play well together. Sure, you can cast latex in silicone, but it's a less than ideal way to do it. Also remember this... Hard casts use soft molds, and soft casts use hard molds (in most instances). In other words, if you're resin casting a bio you would do that in a soft (silicone) mold. Casting a soft mask is best done in a stone mold, meaning plaster. Save you time and money and stay away from plaster of paris. It's not nearly strong enough. There are of course exceptions to every rule, but time and experience has shown the correct way to do things. Ultracal 30 is the way to go, especially if you want more than 1 pull out of your mold. Like with your suit, my suggestion is not to rush into it, do as much research as you can (then do more) and use the correct materials the first time. YouTube has lots and lots of good info from the pros, and there are at least 3 pages worth of topics that apply to this already available here on the lair. If I've learned anything in my time building, creating, and constructing things it's that there are 2 way to do things... the cheap way OR the right way. Ask yourself this... wouldn't the pros do it the cheap way if it was the right way? Ultimately it's up to you, and I really don't mean to come off as an ******* here, but after your "latex problems: thread I have a hunch you're going to do it the way you want, but hopefully this will save you some time, effort, and money. Up to you. That being said, I will leave this topic alone from now on.
Brian