How to make a fillet

no no this isn’t about fish or chicken fillets or anything, its about making fillets based on math and circles; its a continuation from this post. All I need to know is how to even start to script it.

they are discussing about bezier curves, maybe try searching on youtube, it has helped me in the past although it might not be easy.

they are not Bezier curves, they achieve the same effect, but are just better and more suited for my game.