I cut the top off and then a couple of small-ish holes in the sides (larger than her fists) so that she could reach inside.
This is the age at which babies do the same thing repetitively until they have got the hang of it and have added it to their learning “repertoire”. Which is why some babies seem to love dropping things off their highchair repeatedly, because they love to watch the cause and effect of it falling to the floor and being returned to them (much to most parents’ annoyance!)
“Oooo I can fit my whole arm down in here!”
She played with me and Big Sis (who of course wanted to play too) and loved the game of passing the pieces back and forth, dropping and picking up, hiding and uncovering. She then played with it independently for another 10 or 15 minutes seeing what else she could fit inside it and generally shaking it around to enjoy the noise she could make!