1) High tooling costs and long set up lead times. Up-front costs for Children Toy mould are high due to the design, testing, and tooling required. There is the initial design and prototyping (probably via CNC or 3D printing), then the design of a prototype mould tool to produce replicas of the part in volume. Lastly, and only after extensive testing during both stages, you can finally injection mould a part.
2) Part design restrictions. Plastic parts must be designed with injection moulding consideration and must follow the basic rule