This is a remix of my ergonomic hair comb ( https://www.thingiverse.com/thing:1689741 ) adjusted for the typical sizes of baby and toddler heads and hands. Parents can use this initially, and babies will model the behavior within the first year. The label on the handle can be customized, perhaps to the name of the child. This can be a nice way to make a unique gift.
I recommend a very slightly flexible filament like PETG for the teeth to have a comfortable small amount of flex. Depending on your printer's properties, some adhesive on the print bed at the ends of the teeth might significantly help in printing this.