Arts and Family Crafts
Lunar Prospector Model
Four large and three small marshmallows; heavy (white) coverstock paper; scissors; hole punch; soda straws; two highlighter markers (one yellow and one blue); scotch tape, aluminum foil, 15-30 min of time. First, get the pattern and print it out on thick cardstock (consult your printer's user manual to make sure you're able to print on cardstock).
Make a Cassini Spacecraft That's Good Enough to Eat
You can construct an edible spacecraft with some major components of the real thing. The Cassini spacecraft features a large dish antenna for communicating with Earth on the main body. A long boom out the side carries a magnetometer, an extremely sophisticated compass for measuring the direction & strength of a planetary magnetic field.
Galactic Mobile - Family Crafts
From Education World's Space: The Final Frontier lesson plan.
Spacey Things to Make - Family Crafts
From NASA, a collection of fun things you can make. I especially love the pop rocket.