I have an ultrasonic cleaner that I use to restore antique fountain pens. It has actually cracked plastic bodies and it is a cheap one and not very powerfull. I think Nitrogen burst would be ideal but then the law of diminishing returns sets in. When I tank develop, I do rapid inversions and spins to break up the laminar flow of spent developer. It works consistantly well without uneveness or streaking. I an not sold that it can be done any better.