Hydrophobic Maze - Design and Build Project

This is a project I adapted from an Instructable put together by radicalrick and the original can be found here. In my middle school Makerspace class I really enjoy having the kids work through the process of brainstorming ideas and then transferring them to a digital platform and then trying to build with their own hands, that digital design. In this project we start out by drawing out ideas for a maze, after viewing an example, on notecards. Students then recreate that idea in Tinkercad and finally use an svg printout of the maze to guide constructing of a real maze using a sheet of wood and chopsticks. The revision and rethinking that is required to move between brainstorm, 3D model and handmade maze are what make this a great project.

Time required: 5-6 (80 minute) class periods

• 1 class for introduction, brainstorming and intro to Tinkercad
• 1-2 classes for Tinkercad work depending on preexisting skill
• 2-3 classes for physical construction

Student Handout is attached

5 x 7 notecards (127 x 178mm)

Pencils

Razor knife

Scissors

Cutting mat

Sandpaper

Chopsticks

Wood or MDF boards precut to 127 x 178mm

White glue

Drill or drill press with 8mm bit

Paint or markers for decoration

Hydrophobic paint (Rust-Oleum NeverWet Spray)

The first day of this project begins with students viewing an example maze that I have made. I have mixed feelings about showing them examples, because this seems to lock their thinking to one way and one idea about how the maze should look. Without an example though, many have difficulty visualizing how it will work. Over time I hope to add more exotic examples for them to see.

Once they have seen the example and played with it a bit, they are shown the materials they will have to work with and set loose with a 5" x 7" notecard. I encourage them to do a couple of designs and to really be outrageous with one and maybe a bit more conservative with another. For this part I also have them work free hand on the drawing rather than using a ruler to create exacting shapes. Some of them find that the most challenging part of the whole project. They want to be precise right from the start.

After everyone has a couple of mazes drawn on notecards we transfer to TinkerCad. It is a great platform for starting out with 3D design and manipulation. Most of the time my students have limited familiarity with TinkerCad so we spend about 30-40 minutes going over the basics of renaming files, moving and positioning blocks, using holes, grouping, duplicating and changing the grid size and snap grid settings.

There are a couple of things that I have found really help the kids be successful in creating their mazes. First, I have them set the grid size to the same as their notecard. Second, I get them comfortable with toggling through the different snap grid increments to facilitate the movement of pieces in different ways. Third, I make sure that they set the height of their blocks to 4mm so that all of the pieces are the same height. This last point is where the duplicate function really comes in handy.

Since we are working with chopsticks, I have someone measure the width and thickness of one. We then use that measurement to set our first block size in TinkerCad and then duplicate the block for all future pieces. For this iteration of the project our chopsticks were 4mm. You will need to change this based on the size of your chopsticks. As you can see in the pictures, our chopsticks were also round. When we work in TinkerCad though, we use rectangular shapes. This is because they show up better when the svg is printed at the end of this step. I am highlighting the size of the blocks because it is really important that all the pieces placed on the workplane are the same height. The svg output creates a 2D rendering of our 3D shape. This is the same output that would be used for laser cutting. If the heights are not all equal the svg may not show all the lines. Invariably someone will forget this and their printout will not look correct when they want to build. The fix can be time consuming so I try to prevent it as much as possible.

For the layout itself, the students work to recreate their brainstorm as closely as possible. Some of them will start to measure their brainstorms and then adjust the length of the blocks to match. This is a lot of fun (or frustration for some) as they are working to take an idea and give it a true plan. In doing this a couple times, we have found that a distance of 10mm between chopsticks is ideal. This is wide enough for a good size water droplet to move easily and also creates a natural limit on the complexity. An 8mm wide channel works as well, but below that the water starts to get reshaped and tends to break apart more when it is in the maze. Some kids opt for large open spaces and then drill multiple holes to create a different kind of obstacle.

The holes or "traps" as we call them are 8mm in diameter. In the TinkerCad plan they are denoted with a 4mm tall and 8mm in diameter solid cylinder.

Once they have created a plan they are happy with we use the export function to create an svg file and then print it. Make sure when printing that the printer is not trying to scale or "fit" the image. This will result in a print that is not the correct size and the actual build will be very difficult.

The build itself! At this point, students have gone from a rough brainstorm to a precisely rendered model and now need to transition back to physical materials. Chaos ensues!

Ok, only a little. The challenge of transitioning from 3D render to physical materials is that even though the chopsticks have been measured at 4mm in diameter, they are not perfectly made and usually taper at one end. This is compounded by the fine motor skills of most 13 and 14 year olds and their ability to cut with a razor knife or scissors a piece of chopstick to exactly the length they built it to in TinkerCad. I love it! They have to improvise, they have to redesign and they have to troubleshoot on the fly while the glue is drying!

To begin this phase everyone gets their precut piece of wood or mdf to use as their base. We then go over how to safely use a razor knife and scissors to cut the chopsticks and talk about being frugal with the glue. Less is more in this case because excess glue will look ugly and also create weird bumps and shapes in the maze.

Most students will end up using the scissors to score their chopsticks and then snap them off. Some students don't feel this is exacting enough for their standards and so use the razor knife to carefully cut each piece. Much more time consuming, but it meets their needs for precision and neatness. Either way, after cutting each piece to length, students need to sand the cut ends to get rid of burrs and splinters. These will tear the water droplet apart.

Using white glue straight from the bottle or with a fine paintbrush they apply a thin line to the chopstick and place it on the board. Getting the final product to match their TinkerCad design takes a lot of patience and careful measuring. Frequently, students find that their precisely creates plan runs up against the reality of imprecisely machines chopsticks. This makes for a great discussion of adapting to the situation, redesigning and their ability to engineer to such fine tolerances. In the end, all of them are successful in their build and have learned to adapt and think through problems.

Once the glue is dry they go through a safety lesson on the cordless drill. Using an 8mm bit, they drill all their traps. I have them mark the traps in advance using a sharpie so that the drilling goes quicker. Drilling can create ridges and rough spots on the edge of the hole so the students use the razor knife or sandpaper to smooth the edges of the holes. Then they can decorate the maze. The simplest decorations are to show the starting and ending points on the maze. Some want to do much more. This also works well when students finish at different times as the ones who finish first can decorate while waiting for others to complete their work.

Waterproofing is the last major step step and one that my students don't get to participate in unfortunately. Our makerspace does not have a spray room or good enough ventilation to allow us to spray indoors and the process for applying the hydrophobic coat makes it inconvenient to go up and down 4 flights of stairs for a whole class period. I generally do all the mazes from both of my classes at the same time, after school. That way the fumes don't bother anyone. The hydrophobic coating is a two part spray and the first coat is pretty foul. Wear a mask and make sure your ventilation is up to spec if you are working indoors.

The coating works best, I have found, by applying three or four coats of the base layer and then the same number with the top coat. All told it takes about an hour to do. They need to dry for a minimum of 30 minutes before they get wet, but the manufacturer recommends 12 hours. The surface will feel slightly pebbly when dry and also have a frosted look. There is a totally clear version, but I have not been able to get it in Delhi.

Once dry, the students get about 10 minutes to play and challenge each other in class. I bring in some plastic pipettes and cups of water. They have to film a video of someone playing with their maze and that video gets attached to their reflection on the project. I assess them on their thinking about the project and how they viewed their growth and efforts as well as on the physical product. One thing I don't do is judge their artistic skill or the complexity of their designs. I am looking at how they applied the skills we learned and their attention to detail.

If you have ideas for how this project can be improved, please let me know. I am also happy to answer questions.