Scout Ahead https://www.scoutahead.org/plans/model-design-and-building-merit-badge/questions

Which of this applies to you?

Answering these takes the parts that are not for you out of Model Design and Building Merit Badge. Nothing is required, nothing is kept on the server, and nothing is ever hidden because a question went unanswered. A step that might apply to you stays on the list and is marked.

Which model are you building?

You choose this at requirement 3, with your counselor's advice, even though the five options are printed at requirement 4. Everything in requirement 3 then follows from it: the plans are to that option's scale, and the materials and tools lists are that option's. Note how differently sized these end up, and that only the process model lets you agree a different scale.