Category: Design

Design Challenge: The Foam Wood Derby

I’ve always wanted to run a super face paced pinewood derby style race. As I designed some simple, messy projects for the 8th grade as sort of fun one off projects, I decided to make the idea a reality.

The design is simple. Each group (or individual if your group is small enough) has two deliverables. A car carved out of foam, and a top and side drawing of the car. They get a basic set of materials. A block of floral ‘wet’ foam, 2 axles and 4 wheels. And they get a simple set of tools. Basic measurement tools, speed squares and surform carving tools.

I introduced the challenge quickly, then let the students loose. To avoid having students completely destroy their blocks instantly, I made the drawings a prerequisite to getting the carving tools. The drawings could be simple, but I required a detailed full scale engineering style drawing.

Once the drawings were approved, they were off to the races. However, floral foam is mess. Super messy. I had complaints of allergy like irritation, the foam staining white shirts, dust in their eyes. All sorts of things. However, after stressing caution, using aprons and generally being more mindful, those complaints dropped off. Perhaps this would be a good project to do in a larger space or even outside.

With the designs carved, students were free to attach their axles and wheels. I could have stopped the groups and stressed the importance of being patient with this step, being precise and ensuring straight and square axles. However, I let them at it, though I did stress that our speed squares would be a great benefit to this step.

The axles and wheels came from Pitsco. Sure, you could 3D print wheels if you have the time, but laser cutting in wood was too soft and acrylic was too brittle. A soft thermoplastic is what these wheels need to be made of, and at $0.15 a piece, it was worth avoiding the headache.

Finally, we race. I used a scrap board at first…but we really needed lanes as cars continued to collide with one another. I used some foam board to make short walls hot glued to the edge of the board. Problem solved.

A simple single round elimination was enough to have a good final race, while minimizing the winners vs losers. You can even enforce a ‘When you lose, you become a cheering squad member of the team that beat you’, ensuring an exciting final race while making all of the students feel a part of the races through the end.

Finally, have students reflect on the process. I had a short discussion, then had students go and post to Seesaw. I got lots of really awesome reflections, lots of great critical thoughts, some great doodles and awesome photos.

Looking back, this little design challenge went pretty well. The kids loved it, it was inexpensive (~$1.50 per group), and was quick to run. In the future I think it could be slowed down to highlight the engineering drawings in more detail, perhaps print wheels, and focus on nice and straight axle holes.

Part Cost Cost / Kit Source
Floral Foam (72 when halved) 35.50 (price fluctuates on amazon) 0.50 Amazon
Pitsco Axles (100) 6.50 0.13 Pitsco
Pitsco Wheels (100) 15.50 0.62 Amazon
TOTALS 57.50 1.25

Surform Tools – $2.99

Speed Squares – $2.99


3D Printers as Construction Toy Factories

The 3D printer is the hottest tool to bring into classrooms these days. They are the talk of the town. In lots of ways, they are amazing machines. It possibly more ways, they are tricky classroom tools. Most of them take plenty of tinkering and tuning, print times are long (a 1 hour print for all 50 students in a grade can be a week or more in the making), upkeep is time consuming. Lots of little quarks.

However, where they have excelled in my classroom is in printing construction brackets. If we aim to print small parts to be used to let students build bigger structures you can kill a few birds with one stone. Print times are reduced, and you have a build to pull students away from the computer screen.


I wanted to share a few examples, and how I use them in my classroom. First up, the simplest. Brackets to join straws at different angles. I took inspiration from Makerbot’s Speedy Architect project for this one. These pieces are tiny, taking less than 10 minutes on our Printrbot Simple Metals using my super-duper fast printing profile. Currently, the 6th grade is designing architectural models using these brackets. They will be adhering to uniform proportional scale for the structure (about 1″ to 10′), and will be closely monitoring a the cost of production. Straws cost $100 per inch, and 3D prints cost their real life cost, times a thousand, or about $20 per basic bracket.


I’m super excited to see how this project turns out. There are lots of great math connections to the 6th grade curriculum using the scaling and the economy system. The structures are bit innocuous from the structural engineering perspective, but the amount of iterative design & 3D printing we can pull off while printing such small parts will make this project worth while. We are lucky enough that each of our groups of 4 will have their own 3D printer to operate during class time, keeping the project rolling at a fast pace.

Up next, there are the balsa wood brackets, that came from the Zazouck project on Thingiverse. These parts are a bit different than the straws in that I use them exclusively as construction tool. The parts are all printed ahead of time, sorted into different types and they are used to do rapid fire construction challenges. Most recently students were tasked with building a 12″ bridge, while controlling for the cost of parts and materials used to build the bridges.


These pieces are great for rapid construction. They lack in the structural consistency that using glued joints might give you, but they let students build quickly. Often, balsa breaks in the brackets, but a drill bit reams them out pretty easily. These are great bits, and took about 30 mins to print a set of each piece. To get a classroom set of about 20 of each part, I had the machines running constantly for a few days. But now they are done and we have our own custom construction set…in colors that match the labs floors!

Last up, we’ve got the most complicated component yet. The craft stick brackets. These pose the most difficult design process of the three, but I think it gives the most rewarding final product. Requiring constantly being aware of stick orientation in regards to slot location on the brackets. I think the challenge of the design makes these an awesome candidate for creating a lesson on using Fusion 360 assemblies to virtual design structures before printing them. This is something I’ve got in the pipe for the 7th grade next semester.
1025160920All of these follow a basic principle. Find a material that is cheap and plentiful in you lab, and design brackets to join them at different angles. Have students design the parts, even model the whole structure in CAD before printing. Cut down print times, end up with bigger and cooler parts…its a win win all around. Have you done any construction projects like this? Let me know!

Creating algorithmic designs for fabrication in Beetleblocks

I was recently tasked with creating a quick activity that could be done within a booth at the Philadelphia Science Carnival, something that would take only a few minutes to do so kids could filter in and out of the booth. It was going to be tough to do something great with that sort of timeline, and nearly impossible to stock enough supplies to support the 400+ kids that will come through during the carnival. I decided to tap my favorite ‘free’ supply, adhesive vinyl scraps from the sign shop, creating stickers on our craft plotter.


Now stickers resonate with kids in a way I don’t really understand, so I knew it would be a good draw at an event like this, but I wanted to do something less frivolous than just making worthless stickers with a craft cutting machine. So, I turned to code. We could program a cool design, and cut that out. I dove into Beetleblocks and came up with a really simple bit of code that quickly demonstrated the power of code, and the magic of math.

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The code is fairly simple. First we can have students create a square, realizing that we can use the repeat block to make our lives easier. The result is this simple little chunk of code that produces a square.

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Great! We have a square…but that is a pretty boring shape. Maybe we can make it interesting. Now we can start to think about some math. We know that a square is a 4 sided shape, with 90 degree angles in each corner. If we multiple the amount of sides and the angle of the corners, we get an important number: 360 degrees. What if we wanted an 8 sided shape? What would be the angles of the corners?

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Great! Now we’ve learned something important, and we can really get creative with the initial shape that we draw…but a single shape is boring. Lets now create lots of these shapes, and rotate the origin of the shape a bit each time to make something a bit more interesting.

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Now we’ve got something interesting! But look, we can make another interesting observation in this code. We are drawing 6 shapes within the repeat block here….each time rotating by 60 degrees. 6*60 again gives us that magic number 360! So we can create more shapes, and as long as the product of the degrees of rotation and the number of shapes equals 360 degrees.

Now that we have this code set up, we can let students play around with the numbers.

What happens if we have a 360 sided shape with 1 degree angles?
What happens if we nest yet another repeat block?
Can we use operators to automate the math for us?
Can we write our own functions like drawShape or repeatShape?

There are lots of questions that can drive further exploration. In the end, we might clean up our code using custom blocks, or add some math and variables to automate things for us.

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A quick tip of note; to make the lines easier to see, we can change the display port settings in Beetleblocks. Uncheck the grid and the axis and check off ‘Parallel Projection’ to see directly down on our shapes. You can change the color of the background under the settings ‘gear’ icon, and change the color of the line with the ‘set hue to’ block under colors. You may need to zoom to fit as students start to build bigger shapes with more sides as well.

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Now, the problem with this lesson is turning these thin lines into something that can be cut out into stickers, or on a laser cutter, etc. It is easy to cut these lines, simply exporting the .SVG file out of Beetleblocks. The hard part is giving those line thickness enough to create a defined shape. The easiest way I have found is importing the SVGs into Inkscape, giving the path a fairly thick stroke, and using the Stroke to Path tool.

Ultimately, this simple activity can show a great deal of coding concepts quickly. Loops, operators, variable and functions can all be explored. The connection to geometry is obvious, using degrees in an applied way can help solidify how degrees and periodic functions can be used in action. IMG_5068

I’d love to build on this concept to do things like laser cut jewelry, hand coded letters to create signs, continue to drive algebraic math connections while creating complex machinable 2D designs. With the focus on 3D design and 3D printing, the power of 2D line is sometime forgotten.

Experimenting with OnShape

I recently became aware of OnShape during MakerCon coverage on the Make Magazine blog. It looked great. It had alot of the bells and whistles of things like Autodesk Inventor and Solidworks, with sketch based modeling and assemblies. And, it runs in the browser. It looks promising, so I signed up for the beta. Sure enough, only a few hours later, I was given access.

I hadn’t gotten too much time to play with it recently, but I decided to give it a shot today. I wasn’t feeling super inspired to make anything interesting, but I was annoyed about losing whiteboard markers constantly. So, I decided to design a little holster.



It has been a long while since I used a more technical 3D CAD tool like this. I find myself banging out little 2D brackets in Inkscape or simple  3D models in 123D Design, or even Tinkercad more often then needing the toolset of something like Solidworks. That being said, I was a bit rusty, but it followed what I expected with my use of Inventor and Solidworks in the past. On the left, I could see a history of my recent actions, organized by sketch and related feature applied to the features.


For such an extensive toolset, the interface never felt over complicated or scary. I was quickly able to find my tools based on the icons and just natural placement of tools. It was an intuitive little environment. The speed with which the design rendered changes was pretty satisfying as well. I was worried the bandwidth needed for this sort of app could choke it up with complex features, but it seemed to handle everything with ease.

curaIn about a half an hour, I had the model produced and into Cura, ready to be sliced and printed on the Printrbot Simple Metal. STL Exporting from OnShape wasn’t too obvious, but I figured it out with some Googling and guessing. I was disappointed to find out that there is currently no assembly STL export when I was Googling. It wasn’t something I needed for this model, but it would be one of the reasons I’d turn to this tool in the future if I needed to do a complex assembly.


Sure enough I messed up three times. First, I made the holes for the markers too small. Then I made the stopper holes too small. Then, the next print messed up with about 5 minutes to go. But, thanks to 3D printing, I was able to print and check and print again quickly.


Overall, I am solidly surprised. I didn’t think it would be easy to slam functionality of massive tools like Solidworks into a browser based app, but OnShape seems to do it pretty well. I think that the interface is clever and modern, and it can serve as a great step past 123D Design for students in my classroom. It especially serves as a valuable tool for Chromebook based classrooms that lost 123D Design in the browser not long ago.