I have purchased Duplo for three friend’s kid’s first birthday and they have been a hit. Recommended age is 18 months, but 6 months to a year out, they get more

I have purchased Duplo for three friend’s kid’s first birthday and they have been a hit. Recommended age is 18 months, but 6 months to a year out, they get more use out of my gift than the others. Duplo is also compatible with Lego, which means they can be used as filler, etc. as they get older. Now one couple is having their second kid and I need to find a new present!