One could add or replace the usual six-sided dice with other sizes, for example d4s, d8s, d10, d12, or even d20. Assuming that you are keeping the Score (1-3) and Edge (4+) faces the same, this will change the likely result. This is not done in METTLE Core, but other settings or derivative systems could make use of it.

d4s are far more likely to roll Score. A designer could add or replace dice in a pool with d4s to represent a “safe” stance on a task. This would help ensure success but it would rarely be spectacular. Useful for those who are poor at a task or just cannot risk failure.

d8 and up are more likely to roll Edge. Adding or replacing pool dice with these could represent a “risky” stance on a task. This would skew toward amazing results but also drive down the chance of actual success. Useful for all-or-none challenges that must be overcome now, or not at all. Also great for show-offs.

Twists stem from available Edge, so of course they are less likely with lower dice and more likely with higher ones.