We got one for our dd (5yo) last christmas. Was fine till dd(2.5) got hold of it. She pulled loads of the sticky strip through and wasted it then tried to wind it the wrong way and the end of the strip disappeared inside.
I spent ages with a sharp knife trying to re-thread it. it is virtually impossible
We had to buy a new cartridge because most if the first was wasted.
You have been warned!!!
That said, under supervision, they're great!!