This is a great idea–make your own snow globe. Apparently, all you need is a jar, some sort of snow (crushed eggshells or glitter), mineral oil or glycerin, silicone sealer to keep it from leaking, and of course the object to put in the globe. All of this can be found around the house or at the craft store.
There are tutorials on eHow, Berrylicious Buttons, and Martha Stewart.
The creative possibilities are endless, especially if you make your own objects out of baked polymer clay. It’s like a little frozen terrarium for your house.