Epsom salts and food coloring. Make your own edible play sand in vibrant colors- this is a great sensory material for babies who are still in the mouthing stage. While I doubt they will eat much it is nice to not have to worry if they sneak a taste.
Here is a no cost, low prep fine motor activity for you to try with your little ones! Even though I created this for my 11 month old daughter Rowan, Rilynn enjoyed it as well. I put this together in 5 minutes right after breakfast.