How to improve the builder pattern?

Question

Motivation

Recently I searched for a way to initialize a complex object without passing a lot of parameter to the constructor. I tried it with the builder pattern,

Answer 1

The traditional builder pattern already handles this: simply take the mandatory parameters in the constructor. Of course, nothing prevents a caller from passing null, but neither does your method.

The big problem I see with your method is that you either have a combinatorical explosion of classes with the number of mandatory parameters, or force the user to set the parameters in one particular sqeuence, which is annoying.

Also, it is a lot of additional work.