The mini flat elastic laces from U-Lace are suitable for your running or casual sneakers, but also very practical for people with reduced mobility. You will also find a children's collection of "Kiddo's" laces.
Example for a pair of sneakers with 6 eyelets :
Minimum 2 U lace classic packs for adults see photograph below
With a choice of 34 colors and a collection of mix packs, you can compose a multitude of color gradient combinations.
So be the designer of your shoes !