As per cloning... we have the technology. But you'd be in charge of raising yourself up to, oh, whaddyou think?, 14 or so, before you could start buildling stuff. That's 14 years of maintaining the cellar, making sure it puts the lotion on the skin, etc... you don't want to do that!

Ok, back to reality (that was creepy)...

I think that these Curtis and Devin one-shots used half-silvered mirrors, but I know you're set on the beam splitter idea and that indeed could be a great route to take. I've just read numerous accounts in old books about how tight the tolerances need to be to ensure that the 3 negatives are in the identical plane of focus.