Sensory bins are a great way to teach colors to your little one. This one has a blue theme. The base material however is not blue, it is white. The blue colors pop more that way though.
I used a bag of white, lavender scented epsom salt from Dollar Tree as the base material.
Then I added in all the blue things we had laying around for sensory play/bin use. Your objects may obviously be quite different than ours, but the point is that they're blue. You can use whatever you have around the house that's appropriate, small toys, etc.