Looks great to me! I have some Mirror Universe items that need to be finished before I try my hand at something like this.
I've never molded or cast anything, but from what I have read so far, you will likely have to seal your master with a sandable primer and use some sort of mold release agent so the latex doesn't stick. The particular product you mention might be a NO-STICK type of latex, but I'm not familiar with it. Hopefully there are some guidelines for use on the package. Also - you mentioned brushing the Latex on in layers. You may need some sort of outer support shell, or mother mold to hold the latex rubber mold in its proper shape for casting. Hobby Lobby and Michael's Craft stores sell Alumite Casting Kits that use a two part silicone rubber that you may want to try instead of the latex rubber. Silicone doesn't stick to anything but itself and that might help you a great deal. The only drawback that I see at this point is that you might need to make a two-part mold to get all the details you have added to your scratch built agonizer. Again, I have no practical experience at all - everything I've written so far is simply based upon what I have seen done by folks here at the RPF, and what I have read. I know just enough to be dangerous. You've picked a great subject for your project - it just might give the word "agonizer" a whole new meaning before you finish! Good Luck!
TI-6212