A model kit consisting of magnetic rods and steel balls, which is generally sold as a desktop toy, has been utilized to construct physical models for teaching packing arrangements of metallic crystal. All four basic metallic crystal structure models are easily constructed layer by layer, and corresponding unit cells can be naturally derived from the packing structures. The low-cost models based on magnetic rods and steel balls are portable and easy-to-construct, and teaching practice shows that they can guide students to gain a deeper understanding of packing arrangements of metallic crystal. Positive feedback from students indicates that they are interested in constructing models with the rods and balls by themselves. Overall, compared with the existing crystal structure models, these models combine the characteristics of portability, low cost, and ease of construction; therefore, they have great potential to enhance students' learning of metallic crystal structures through hands-on activities or classroom demonstrations.