From all of the echo dot v3 mounts this was the one I liked (thanks kikets for the original), but I needed it to fit a UK wall socket.
I've altered this in tinkercad, this was my first time using it. I didn't round all the edges on the plug but it fits pretty well.
Be careful removing the supports, I managed to crack one of the fins that holds the dot in place although it's still usable.
Edit : I originally printed this at 0.3 resolution and 20% infill but the fins which hold the dot in place we’re too thin so I’m going to have another go at 0.2 and 100% to make it stronger.
Further edit : I've just found some settings in cura that allow you to add an overlay mesh to an object and change the slicer settings for the part of the object covered by the overlay, so I'm now going to print this with 20% infill for the bottom 36mm then 100% for the top part.