Specialized Filaments: Dual-color, Tri-color and Rainbow. prints often require specific types of filament that blend colors or multi-filament systems. These materials are typically more expensive than standard single-color filaments.
More Complex Setup: Multi-color filaments can complicate the setup. The printer might require more calibration, and there’s often an added step of ensuring color alignment. This increases the labor involved before printing even begins.
Extended Print Time: Tri-color and dual-color prints take longer to produce, filaments, or precisely layering different colors. Since time plays a significant role in the overall cost of 3D printing, the added time required for multi-color prints results in higher pricing
Risk of Errors: Printing with multiple colors increases the likelihood of print failures or defects due to alignment or blending issues, leading to wasted materials and time. The increased risk requires extra care and testing, which drives up the cost.
Maintenance and Wear: Printers used for multi-color printing are often subject to more wear and tear and additional mechanical strain. The maintenance costs are higher, which has to be factored into the price.

Shardscale Dragon - Short