Catcher's throwdowns
Place empty bucket on the base. Catcher get behind the plate and have someone toss (from 10-15 feet is fine) ball to him and then he throws aiming for the bucket.
Outfielders' Throwing
Place empty bucket on homeplate and have outfield go to position. Hit them a groundball/flyball and have them throw aiming for the bucket. Good to have a "relay man" in the "relay" position with their hands up. Was always taught to aim for the relay man's logo on his hat. Throw "through" the relay; not "to" the relay.