12 Days of Christmas figurines to put inside glass X-Balls.

My daughter wants to work on creating Christmas tree balls (she has the clear glass ones already) to create balls to sell--in sets of 12--which would depict the "Twelve Days of Christmas " theme.

Her idea is to create small enough replications of all the named characters in the 12 days of Christmas theme inside each ball.
The requirements would be:
1--They would have to fit through the holes on top of the X-Mas balls.
2--What substance could she use to fill the base of the balls that would provide a base for all the "characters" to sit on, but that would
be lightweight enough for a X-mas ball. So far, she has just used melted glue-gun glue--which is quite heavy. Is there any other
substance that could be "blown"into the balls and harden in a leveled field --but be light weight????

Mind you--the hole at the top of the ball is about 1/2"-5/8" in diameter. Anything she would insert to create the 12 days scenario would have to fit through this hole.

Does anyone have a site where miniature X-Mas figurines could b purchased from for this kind of a project?
How about some sort of a "filler" that could be sprayed into the balls to create a snow-covered base--but lightweight?

Throwing this out to you all talented people to see what you can suggest....

Thanks, Gita