I got this wonderful idea from a colleague at another branch in my system. Basically, you use chalk to color salt and then use it to make sand art. I already had some chalk, so I bought a bunch of salt (I estimated one container of salt would fill about 2 bottles). I bought some sand art style bottles and necklaces at A.C. Moore for around $1/piece. (My colleague used empty water bottles.) I also bought a few small funnels.
I had the kids fold a piece of white scrap paper in half, then pour some some salt onto the middle of the paper. The fold make it easier to pour later on. They then took a piece of chalk and slowly (but firmly) rubbed the chalk against the salt, causing little bits of chalk to come off and color the salt. They liked experimenting mixing chalk to make their own colors.
Then they picked up the paper and using one of the funnels, poured the salt into their bottles. It was fairly easy for the kids to do, although the little ones definitely needed help with the pouring of salt. It did make a bit of a mess, but it was easy to clean up since it was sweepable.
The kids loved it. Everyone from preschoolers to teens wanted to try it, and many of the adults were disappointed that I didn’t have enough supplies for them to make one, too. (Would be a great family art project in the future!) I will say that it did take quite awhile to make enough salt to fill the whole bottle. After realizing this, I recommended the younger kids opt for the necklace pieces (much smaller) or include some white in their designs (plain salt).
Here is a simple video I found on YouTube, if you want a visual of the process.