In physics, the difference between elastic, inelastic, and perfectly inelastic always confused me. Looking at trends and patterns based on physical replicated scenarios helped clarify different concepts that I otherwise would not have understood. Usually, such devices include electronic components that allow for it to better simulate the lack of friction on the disks. This causes the price to be around $70, whereas these 3D printed ones provide a similar, yet not exact replicated, lab simulation for a notably lower price.