Find a leg press machine and get ready for an intensity technique that'll set stubborn calves on fire and get them growing.
Start with one calf in the stretched position (toes toward shins), then press the weight up with both feet and hold the contraction for 3 seconds. Then use the other leg to lower the weight by itself and hold the stretch position. And again, use both legs to press the weight back up.
So whenever you lower the weight and hold, only use one leg and alternate between left and right. Once you hit failure, you can extend the set by using both calves during both the lowering and the lifting.