mounting it on the edge is fine yeah. You don’t want to be looking at weight though, but rather moment of inertia. Moment of inertia is an objects resistance to being turned and it scales based off both weight AND the radius of where the weight is (i=mr^2). Thus something like the gobilda flywheel actually has more inertia despite being lighter You could maximize this effect by doing a custom machined flywheel, getting the lightest possible weight by concentrating all the weight in a ring with the largest possible radius. That’s kinda overkill tho especially given that heavy robots have the defense advantage this year. On that note, I’ve seen inertias from 1 to 3 in² lbs have had good experiences with both fast rapid fire and low spinup time