Marc Brunet Aug 28, 2013:

What does a prawn tail really look like? Thank you for your interesting challenge, Krzysztof. Nevertheless, precisely based on the drawings you refer to, am still supporting the "Mitered" version. Why? it resembles the dorsal plate articulation of the prawn's tail far better than the "corrugated" version you favour. Actually if, from your image selection, you had selected the "adjustable" elbow, would have accepted it as a possible alternative, with qualifications. But whether or not the composite bend angle of those 'Prawn Tail look' models can be adjusted by swivelling one or more of their component sections, all (adjustable/welded) sections of such elbow types have to be cut at a set angle, and so must rely on a mitre for their manufacture. Don't Agree? :-)