An AI to measure feet using a photo?

I am a passionate user of AI, but am new to developing it. There are now tons of ingenious AI tools that make your life easier. So I wanted to ask for a few tips and tricks on how I can put my plans into practice!

I'm planning to develop an AI that can determine the exact dimensions of a foot based on a picture of it. To do this, the foot is to be positioned on a sheet of paper in order to determine the size of the foot based on its standardized measurements and to recommend a suitable shoe size.

So an AI is needed that can recognize objects and create a coordinate system based on the sheet of paper to determine the size of the foot.

Are there any similar projects that can be used? And what should I generally bear in mind during development and how do I proceed?

Thank you very much for your attention!