My daughter got a slushie cup for her birthday this year, it was about £12 on Amazon. Similar concept to an ice cream machine - cup goes in freezer for 12 hours, take it out, add drink and squish for 3 minutes, instant slushie. We just use squash so it’s not full of crap like normal slushies. She thinks she’s won cos she gets a slushie every day! You could also buy the proper slushie mix or use fizzy drinks or fruit juice. You could get them one of those each?
She has recently got back in to her magna tiles (5th birthday present) but can’t see her using them at 10.