So after sensory bottles, we've sensory boxes. The great thing is that the boxes are stackable. I got this idea from Mess For Less, which showed rather tiny transparent boxes that are quite difficult to find so I just opted for the food microwavable containers. I also didn't hot glue the boxes because I will like to reuse them again next time for other activities. The cons about using a rather big box is that my baby gal started stepping on them once she learned how to stand so now I make sure the boxes are played on her playmat and with supervision.
I used whatever's available in my house, didn't buy anything at all, except for the really budget boxes. The items in each box are: torn paper (look at the happy baby!), pom pom balls, uncooked pasta. She looks at them, shakes them and sometimes as I've mentioned, step on them! And now that she's older, I let her play with the contents inside like getting her transfer them to a bowl or to a basket. Sometimes she just enjoys throwing all the pom pom balls around for crazy brainless fun. The activities are endless! Soon, she will be able colour sort the pom pom balls, do a collage with the torn paper or try to scoop the pasta with a spoon. Actually we've not bought Noe any toys since she was born but she's got a lot of all these interesting DIY ones!