Marcos at Topsolitario offers a set of free paper models of cargo containers for your modern and futuristic miniatures games. They are quite lovely. There’s even a video showing how to build them.
Steel Rain is a set of rules for 1/300 scale science fiction miniatures.
Your science fiction troopers need a utility hovercraft to get around in. Here’s a nice paper model of just such a craft.
For Infinity and other science fiction games, here’s a paper model of a Chickenhawk dropship. It comes in a couple of different versions.