Is having the numbers in sequence the best idea or should they be scrambled on the wheel? When making dice, the pips are placed in such a way that they balance themselves. Balance isn't a problem with this spinner, but perhaps it would "feel" better, if they were in a more random order. And why do they have to be numbers? Pips or even pictograms could be used instead.
Could the spring be replaced with something that is printed in 3D? Plastic is flexible and printed springs have already been proven effective. Perhaps one of them could be incorporated into this project?
This project could be extended in other ways. A D6 roller is fine, but how would a different number of options work out? The gear is designed to stop the numbers in specific places. Eight numbers and hence eight teeth on the gears would probably work fine, but how could a D20 be implemented?
What about a 2D6, spinning two disks simultaneously and outputting two different numbers. Perhaps the finger switch underneath...