Yes, both materials are good for kid’s wheelbarrows. Plastic is usually preferred for making toy wheelbarrows for the smaller kids. Such wheelbarrows won’t be able to withstand heavy use, so they are mainly used for carrying toys and dolls. Metal is good for slightly bigger wheelbarrows for older kids. Since metal is more durable, these wheelbarrows are preferred for lifting brush, dirt, rocks, and soil. They are also more durable. The only thing that differentiates them from wheelbarrows for adults is the slightly smaller size.