Model Design and Building Merit Badge

Read requirement 4 before you start requirement 3

Requirement 3 is headed "Planning Your Project" and its opening instruction is this:

With your counselor's advice, select a subject from requirement 4 for your model project. (You must not use a pre-made kit; your project must be your original design.)

So the badge sends you forwards. Everything in requirement 3 depends on which of requirement 4's five options you take: the plans in 3(a) are drawn to that option's scale, the materials list in 3(b) and the tools list in 3(c) are that option's materials and tools.

The decision is made at requirement 3. Requirement 4 is only where it is carried out. That is why this plan asks you which model you are building at the point where you are planning it, rather than at the point where the five options happen to be printed.

The five options, and how big each one ends up

The badge prints a ratio. What matters when you clear a table is a size.

Two things follow from that table.

4(c) needs the most space and it is the only one you can renegotiate. Its wording is the only place on the badge that says "or an agreed upon scale". If two and a half feet of plumbing diagram is not going to work in your house, that sentence is your route out, and it is a conversation to have at requirement 3 rather than halfway through.

4(d) has no scale at all. It is the only option free of that constraint, which is worth knowing if the arithmetic of scale is the part you were dreading. It has its own condition instead, described below.

The book's metric conversions are wrong. All of them.

This matters because a counselor may be working from the printed book.

Every one is written the wrong way round. A ratio of 50:1 describes a model fifty times larger than the real thing. Three of the five are also simply the wrong number, rounded to something tidier than the arithmetic allows.

The current page prints all five correctly, and arithmetic rather than authority settles it: a foot is twelve inches, so a quarter inch to the foot is one part in forty-eight. Use the fractional scale, which both sources agree on, and ignore the parenthesis in the book.

Requirement 4(d) is the one with an approval in it

Four of the five options ask you to discuss and then present. One asks for something more:

Once your design is approved by your counselor, build a working physical model.

That is an approval on the design, before the build, and it is unique to 4(d) among the five. It cannot be granted retrospectively: a device built over a weekend and shown afterwards has skipped it. Note also that 4(d) is the only option whose wording insists the model be working.

Requirement 5 is a second model

It is easy to read requirement 4 as "the project" and requirement 5 as a postscript. It is not. Requirement 5 asks for a fantasy spacecraft: real-world research in 5(a), individual components designed in 5(b), a final sketch or rendered image from multiple angles in 5(c), and a full discussion in 5(d).

Whether you must physically build it is genuinely unclear from the text, and this is worth settling before you start.

None of the four lettered parts asks you to assemble anything. The printed book's version of 5(b) said "arrange and assemble the parts" in those words, and the current page has replaced it with designing components. 5(d) then accepts digital materials.

This page does not rule on it, because it is your counselor's call. Ask the question at the start. The difference between a rendered spacecraft and a built one is several weekends.

Four conversations with your counselor, and the first one is a gate

Requirement 1 is the one people treat as a formality. It is not: its own wording puts it before the project starts, and it is now three parts rather than one, because 1(b) covers digital safety for design software and fabrication tools, which did not exist in the printed version at all.

The Model Design and Building merit badge, drawn so the choice hidden in requirement 3 is made with requirement 4 in front of you. It is not a copy of the requirements: each step is a short label with a link to the official requirements, which are what actually governs and which change from year to year.