I think the real question here is; are you prepared to spend the rest of your life eating nothing but watercress, bread, and the odd insect?
If you decide that the life of a duck is for you, it’s a long and painful journey to complete your transformation.
Firstly we look to the Mursi tribe of Ethiopia. In this group, one display of beauty is characterised by the size of the lips. To achieve really large lips, small dishes are inserted in front of the teeth and left in place to stretch them out. When started at a young age, these lip plates can increase in size to huge diameters, some as big as 12”! For your own purposes though, an oval disc of around 5-6” would suffice to create a standard beak.
You would need a back brace to achieve severe lordosis of the spine (that is, an abnormal inward curve of the lumbar area) to increase ability to tail-feather shake. This is an essential aspect of duck behaviour.
A simple skin graft will suffice to create webbing between the toes. However, if your toes are not long enough to create adequate water resistance, the more complex and painful procedure of breaking and re-setting the toes to extend them may need to be carried out.
It is possible to successfully transplant feathers from dead birds into living ones; however, any feathers you may have implanted into the skin would be excruciatingly painful and not take permanently. We don’t have that technology yet. You could have transdermal implants in socket form and insert the feathers into these, but the feathers would need regular replacement and there is a high risk of damage and scarring to the skin if anything got caught or became infected. Your best bet would probably be to modify a wetsuit or similar skin-tight outfit with the feather pattern of your choice. Aftercare would be a much simpler job.
If you wish to go in the water and eat free bread at the park, you will need to consider how to float and maintain your centre of balance. Real ducks have hollow bones, a luxury you cannot gain through any amount of surgery.
You will need a special gland called a uropygial gland to produce the water-repellent oil which allows your feathers to trap air for buoyancy. Where this gland goes is up to you, but I suggest it replaces the spleen, with the oil release mechanism at your belly-button. You will also need an internal system of air sacs implanted in a similar fashion to bagpipes, so that you can squeeze them empty to submerge.
Once you have the feathers, the beak, the webbed feet, the pond skills and you have practised your ‘quack’, you’re ready to be a duck!
Unfortunately, after all of this surgery and custom equipment, you will find that you’re still human-sized and all the other ducks are scared of you.