They cast the remaining original props they could find and the kids mod them as the film goes along. I'm told very much video game style. The PKE Meter especially has some new functions. The jumpsuits allegedly have a "greenish" tint to them this time around.
First of all, I couldn't resist doing the first pic. Second, I agree, there's not much there to work with, so I took Mike J's pic and enhanced THAT by removing the grain.