How does infill percentage and supports affect the final cost?

Infill percentage directly affects part weight and therefore material cost. A 20% infill can reduce filament consumption by 30-40% compared to a solid part. However, it also increases print time, raising electricity costs. Supports add extra material that is not part of the final piece (between 5% and 20% extra depending on geometry) and require removal time during post-processing. The key is finding balance: use low infill for visual parts and high infill for functional parts, and minimize supports by properly orienting the model in the slicer.