Model supports multicolor printing on single material FDM printers by changing filament at specific layers for design effects. I printed the examples in the photos by manually pausing and changing filaments, M600 gcode operations should be effective too.

Scaling up to fit adults will not be an issue, scaling down much further than default size could risk issues with fine details.

Designed for printing at 0.2mm layer heights, accommodates 0.3mm first layer ok too.

Otherwise use well tuned settings for TPU printing, some of the details/outlines are thin and require well tuned flow rates, retractions, etc.