I wasn't sure from attached photo, if front surface of mixer is flat or curved, but it seems from another photo https://www.sinkwarehouse.com.au/products/fiona-basin-mixer-black/, that surface is flat, therefore i decided to use that procedure, only as an exercise, but it exists more than one solution of course.
That's a much better photo and line drawing. On the original silver photo I was seeing slight curvatures, which made the front face more complex to model.
