@artemis I think it's awesome your brother is handing out ICE whistles. In case he's unaware, it's a good idea to make sure the printer nozzle is lead free and the machine is kept clean, for anything going in the mouth. Also, the crevices can trap bacteria.
The article below, aimed at people making musical instruments, suggests either:
- seal the 3D print with a food-safe sealant
- or use the printer to make a mold of the object and then cast with food-safe material