Hi everyone =) I'm new! Nice to meet you
Anyways -- I have made both of these with kids at Christmas time and it went really well!
We made Christmas reefs one year with puzzle pieces. We took a cardboard cut out of a circle, glued the picture of the kids in the middle, and then placed small puzzle pieces spray painted green around the edge. Then we took red glitter and glue and made little "ornaments" on it. They are very cute.
One year we also took star fish and painted them to look like Santa Clause. Here is a picture similar to what we made http://www.octopusisland.com/images/Christmas/Star%20Santa%20real%20star.jpg
Although the kids can obviously not make them that detailed. The parents LOVED those!