Batarang
My son has been wearing batman outfits a lot recently so I decided to make him a cosplay accessory. I printed it with flexible filament so that it is relatively safe as a toy.
Different brands/makes of flex filament have different stiffness properties, so experiment with infill & wall thickness to dial in how soft/flexible you want the toy. I found that using only 5 top/bottom solid layers & 10% infill gave me a batarang that was stiff enough to hold its shape but soft enough that I'm comfortable handing it to my baby.
If you have curling issues while printing I recommend trying a brim.