Great post Steve! I had forgotten some of those properties for selenite! How cool!?! 
Like anything else, the only way to know is through experiment and trying new things. I must admit my last batch sucks! LOL I had read what Josh posted about how to mix things and their order/proportions, and trying to switch up in mid stream, so to speak, I got my mix out of whack and some not so good results. But the GREAT thing is, as Josh mentioned, I can now just reuse the oops in some larger new pieces. I’ve got to buy more plaster, finally killed off the first bag from just making smaller pieces, but will buy several bags so I can get several larger ones made next.
My daughter has painted everything I’ve made to this point, LOL, which is all good. She loves painting them, it makes her SO HAPPY, like a little child with finger paints. She even told me she doesn’t understand why, but she wants more of them around her, all the time! I promised to put up some shelves in her room so she can start displaying everything she has painted on them… well that, and to make a million more pieces for her to paint…. LOL My son has decided to go the commando route, and leave his “butt naked” for now… but also has four pieces in his room. He swears his creativity is going bonkers, he is into doing virtual mixing of music and is having a blast these last several weeks since I first made some pieces.
I share this to add to our body of knowledge. I have meditated with one smaller piece on my 3rd eye several times, it sends me to the outer realms of time and space, the energy is so HIGH, and pure. I’m seriously thinking of making some small muffin size pieces this next go round as well, so I can do some fun things with grids (like under my bed) and throughout my living space. It seems already that the invisible realm that my two cats see, has gotten really busy as of late, they are constantly leaping about, as if to swat invisible butterflies…..
Tony