Model Design and Building Merit Badge
Six requirements drawn so the choice buried in requirement 3 is made with requirement 4 in front of you, and so the scale, the size and the second model are all visible before any planning starts.
7 steps (20 parts inside them). 5 parts depend on questions you have not answered yet. · Version 1, published 13 August 2026 · About Model Design and Building Merit Badge
No questions answered
This is the whole plan: everything that could apply to anybody. Answering the question at the address above takes out the parts that are not for you.
Which of this applies to you
You have not answered anything yet, so this is the whole plan: everything that could apply to anybody. Answering one question will take out the parts that are not for you.
The steps
Stage 1 of 7
1 step
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1. Safety, discussed before the project begins Often forgotten Requirement
THE STEM SETS A DEADLINE: all of this is discussed with your counselor BEFORE you begin your modelmaking project, and you explain why each procedure matters. Three parts now rather than the single paragraph the printed book carried.
THE STEM PUTS THIS BEFORE THE PROJECT, NOT AROUND IT. The requirement says to discuss all these safety procedures with your counselor BEFORE beginning your modelmaking project, and to explain why each one is important rather than simply listing them. It is easy to treat as a formality to be caught up on later, and its own wording refuses that. Note also that this is three parts now where the printed book had one paragraph, and the new part is 1(b), digital safety for computer design software and digital fabrication tools. That applies whether or not you go on to use them, so it cannot be skipped by choosing a traditional build.
Stage 2 of 7
1 step
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2. Types of models, tools and materials Requirement
Three explanations, and 2(a) is the one that matters most for what comes next: it names the same five model types that requirement 4 offers as build options, which makes this the requirement where you learn what you are about to choose between.
Stage 3 of 7
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3. Planning: choose from requirement 4, then plan it Often forgotten Requirement
THE REAL DECISION POINT OF THE BADGE. Its first instruction sends you to requirement 4 to pick one of five subjects, with your counselor's advice. No pre-made kit, and the project must be your own original design. Everything below is then specific to what you chose.
THIS REQUIREMENT SENDS YOU FORWARDS, AND IT IS THE REAL DECISION POINT OF THE BADGE. Its first instruction is to select a subject from requirement 4, with your counselor's advice. Requirement 4 is where the five options are printed: architectural, structural, process, mechanical, industrial. Everything else in requirement 3 then belongs to whichever one you took, because the plans in 3(a) are drawn to that option's scale and the lists in 3(b) and 3(c) are that option's materials and tools. So read requirement 4 in full before you do anything here. Two other things live in this stem and are easy to skim past: NO PRE-MADE KIT may be used, and the project must be your own original design. Those are not advice, they are the condition of the whole badge.
5 parts
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3(a). Prepare the plans, to the proper scale Often forgotten THE PROPER SCALE IS NOT PRINTED IN THIS REQUIREMENT. It is printed one requirement later, with whichever option you chose, and the five differ by a factor of six. A house at the architectural scale of 1:48 is about ten inches across. The same house plumbed at the process scale of 1:16 is about thirty inches across, which is a different kind of object and a different amount of table. The mechanical option imposes no scale at all. Only the process model allows a scale agreed with your counselor rather than the one printed. Settle which option and therefore which scale before you draw a line, and if space at home is the constraint, say so while the choice is still open.
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Stage 4 of 7
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4. Build the model you chose in requirement 3 Often forgotten Requirement
The five options are printed here but chosen a requirement earlier. The stem adds its own condition: before beginning any model, discuss your approach with your counselor, including possible use of CAD or 3D modeling, and present both your plans and the completed model.
THE PRINTED BOOK GETS EVERY METRIC CONVERSION ON THIS REQUIREMENT WRONG, AND YOUR COUNSELOR MAY BE WORKING FROM IT. The 2025 Boy Scout Requirements book gives the architectural scale as 50:1, the structural as 8:1, the process as 15:1 and the industrial as 10:1 or 25:1. Every one of those is written the wrong way round, and a ratio of 50:1 would describe a model fifty times larger than the house. Three of the five are the wrong number as well. The true values are 1:48, 1:8, 1:16, 1:12 and 1:24, which is what the current page prints. Arithmetic settles this rather than authority: 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 state identically, and ignore the parenthesis in the book.
5 parts
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4(d). Mechanical model: a working device, approved first Optional May not apply Often forgotten THIS IS THE ONLY OPTION WITH AN APPROVAL IN IT, AND THE APPROVAL COMES FIRST. The requirement reads: 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 cannot be granted retrospectively. A device built over a weekend and shown afterwards has skipped a step the badge asks for. Two other things are particular to this option. It is the only one of the five with NO scale imposed, which makes it the route to take if the arithmetic of scale is the part you were dreading. And it is the only one whose wording requires the model to be WORKING, so at least two of the six simple machines have to actually do something.
Stage 5 of 7
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5. A fantasy spacecraft: a second model Often forgotten Requirement
NOT A POSTSCRIPT TO REQUIREMENT 4 BUT A SEPARATE PROJECT. Research, component design, a final drawing from multiple angles and a full discussion. You determine the scale yourself, and whether it must be physically built is a question worth settling with your counselor first.
THIS IS A SECOND MODEL, AND WHETHER YOU MUST BUILD IT IS NOT CLEAR FROM THE TEXT. Requirement 4 reads like the project and requirement 5 like a postscript. It is not: it asks for research, for individual components to be designed, for a final sketch or rendered image from multiple angles, and for a full discussion of process, scale, materials, engineering and difficulties. On the build question, the requirement is genuinely ambiguous. Its opening sentence says design and build. None of its four lettered parts asks you to assemble anything, 5(c) accepts a rendered image, and 5(d) accepts digital materials. The 2025 printed book asked at 5(b) for the parts to be arranged and assembled, in those words, and the current page has replaced that with designing components. This page does not rule on it because it is your counselor's decision. ASK AT THE START: the difference between a rendered spacecraft and a built one is several weekends.
Stage 6 of 7
1 step
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6. Explore a career, and research one properly Requirement
Careers only: unlike many badges in this library there is no hobby alternative here. Training and education needed, costs, job prospects, salary, duties and advancement. Entirely desk research, so it fits any gap while glue or paint is drying.
Stage 7 of 7
1 step
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Counselor signs it off Milestone
The completion date is the date you met the requirements, not the date of the signature.
Usually comes after 6. Explore a career, and research one properly.
Merit badge requirements are republished annually. A Scout beginning work uses the requirements as they stand then; a Scout already working may finish under the ones they started with. Guide to Advancement 7.0.4.3 governs which applies. This page records the date its copy was read. Check it against the official page before relying on it.
This plan is a planning aid: the current Boy Scouts of America publication is always the authority, and the sources used here are listed in full. Each step names its own.