This is my latest design for a fiddle yard. Based on many simple theories - cassettes, sector plates and turntables.
As you can see, both the locomotive turntable and cassettes can rotate 360 degrees by way of a pin in a slot that runs the width of the fiddle yard. The area at the back stores two cassettes whilst the other one is being rotated.
Whether someone has done it before I have no idea, but after many failed sketches I came up with what seems to be a feasible fiddle yard with little need to even touch rolling stock.
The cassette/train turntable/approach tracks will all be lined up using the peg and tube method.
If you have any questions/comments feel free to add them!