I've found different ways to add smaller increments to certain equipment in our gym. For example, for cables (where each plate weighs 15 lbs), I place a 5 lb or 10lb dumbbell above the first plate. For fixed barbells, I tape a dumbbell in the middle of the bar with a kind of stretchable band with velcro.
The dumbbells in our gym have fixed weights at 5 lbs increments from 10 lbs to 30 lbs, and 10 lb increments for heavier dumbbells. Is there a way to add just 2.5 lbs or 5 lbs? I'm thinking about something which can be worn in the hands (weighted gloves?), wrist or forearms, and I don't know if there is even such a thing.