Props can help enliven a gaming session. They can create a greater sense of immersion, or they can show off in-game features or objects so the players get a better idea of what their characters are seeing. Simple props include printing out letters or documents so the players can read them. Use appropriate fonts and print on textured paper, perhaps even artificially age the paper by crumpling or singeing it.

You can go further and make mock-ups of statuettes or other macguffins. Full sized reproductions of monsters would be pretty cool. Imagine filling a bedroom with a gelatine mixture to make a gelatinous cube.

Transcript

Chewbacca: Say... Pete?
R2-D2: Yes?
Chewbacca: I... could use your help with something.
R2-D2: Go on...
Chewbacca: I need to make a science demo for my teaching course.
{beat}
R2-D2: Okay, we'll need dry ice, twenty balloons, a tank of helium, a wooden duck, and a kilo block of sodium.
R2-D2: I'll bring the rest.
Chewbacca: Let me rephrase. I need to make a safe science demo for my teaching course.
R2-D2: Okay, skip the balloons.