I had a nightmare trying to find a replacement part for a broken tap in my bathroom. I couldn't identify the manufacturer of the tap so I grabbed my calipers and took a shot at designing a replacement part myself. I used OpenSCAD so that it was easy to iterate on the dimensions to get a perfect fit. To be honest I was surprised it worked (as was my wife), but happy to have saved some money and some otherwise functional taps from the scrap heap.