Cantilever Project [ Chris, Ambroise, Auriel ]

The Task:

The task is simple. Create a structure that extends horizontally from the edge of a stack of textbooks. Next week you will be building the weights that we will use to destroy said structure.

The Rules:

1) You must design the “platform” for the weights so that it is greater than or equal to 12 inches away from the edge of the  surface at the top of the stack of textbooks.
2) The “platform” for the weights must be at least 3 inches wide by 3 inches deep.
3) You cannot have any vertical supports that are touching the ground underneath the structure.
4) No part of your structure can be more than 4 inches below the plane of the top surface of the textbooks. You can build as high as you want.
5) Your structure must have a section to rest on the top of the text books that extends at least (>=) 8 inches away from the textbook edge. This will be where one member of your team place their hands to provide the counter balance. (see diagram)

The Materials:

  • The 30 sticks of balsa wood provided (or less)
  • The amount of glue in the one bottle provided (you are allowed to dilute the glue with water during the building process)
  • no more than 5 ft of “general sewing” cotton thread.


The goal of our cantilever was to spread the pressure caused by the heavy objects throughout the structure, and into the shelf. To do this, we sketched out possible scenarios and blueprints for how we thought the energy should be propagated.

It is important to know that none of us have any engineering/architecture background, the concepts were purely thought from the head, and replicated on paper. Because of this, we ended up with a design centered around a super structure (is what we call it). This super structure served as a strong mass that could hold its branches in place. 


(With the super structure in the middle, we started planning the height of the construction as well. As you can see, the poles are reinforced by adding more wood instead of just 1 rod)


We proceeded with a post-and-lintel type of pattern, very basic and highly inspired by KAPLA, a wood construction game that we played when we were younger, as well as Japanese vertical and horizontal architecture.


The long arms that make the CantiLever were built by binding many wooden rods together, and applying the Elmer’s glue as binding, much like ciment. The string you see in the above picture bound the thick arms to the long rods that were “stretched” across the entire length of the construction.


* very important *
These rods were then aligned with the arms, passed through the super structure, and bound to the back. The interesting part is where the rods meet the super structure. The post-lintel pattern enabled us to pass the rods THROUGH the architecture, while the horizontal rods kept it squeezed and tight into place. No glue needed on this area of the project.


When we brought the structure to test out in class, we were amazed by how much weight it could hold. We held the proud position of 2nd place. As expected, the CantiLever snapped around the base of the arms and superstructure, right where the wood meets the corner of the shelf.


Final project

For my final project, I wanted to explore further the possibilities of making molds with bio plastic. On my first approach I had problems with shrinking process after cooking the bio plastic. I read that “wood flour” or “saw dust” should prevent from it. Additionally, I wanted to explore food colors and tattoo colors.

First I printed a new 3D object on the Makerbot and made a mold out of it:






Comparing to my last bio plastic experiment, my second attempt didn’t went out that well.
I figured out that the colors I used delay the drying process of my bio plastic. Last time I used special sculpture colors. Furthermore, the casts were extremely brittle.

The recipe I used was: 
1 table spoon | Corn starch
1 table spoon | Water
2 tea spoon | Glycerin
1 tea spoon | Vinegar

Ingredients Properties
Vinegar | Less brittle
Glycerin | Flexibility / Moldable
More Starch | More rigid
More Water | Less consistent

The colors I used:

Without colors:

Red food color with “wood flour” / “saw dust”:

Cast with red food color:

Cast with black tattoo color:

Another tattoo color:

Cast with only food color:

Biodegradable Plastic Option From Shrimp Shells

The Harvard Wyss Institute for Biologically Inspired Engineering went looking for a different bioplastic base. Chitin was an obvious answer. Most famously the main ingredient in crustacean shells, it also appears in the wings and armor of many insects and the cell walls of fungi, making it, according to the Institute, the second most common organic material on Earth. It can be thought of as the invertebrate version of keratin, which mammals use to make fur, claws and fingernails.


Straw+polypropylene 3D printing fillament


Designed by a Chinese company called Jinghe, the material is made by grinding up various dried crops like wheat, rice, and cotton, which in China is typically burned to get dispose of. The sawdust is then mixed with additives like polypropylene, silane coupling agent, and ethylene bis(stearamide). It is then extruded into a pellets of uniform size to allow for easier processing. From there it can be used for injection molding (melting temperature between 160-180°C), or further extruded into filament form.


Bio-Plastic Variability Tests

Group Project Participants: Ambroise, Auriel, Chris, Nicholas

Objective: Testing variability of each ingredient to see how each component reacts with different input amounts to produce a bio-plastic.

Scope: Cooking 4 different batches examining the results when an individual component amount is increased by 300%. The basis of a 300% increase in the component amount is drastic characteristic change in the bio-plastic.

Base Recipe


Post-cook: Gelatinous, slimy and sticky, more congealed than syrup, after rubbing and spreading plastic does not hold form together.

After 6 hours of drying:

  • 1 tbsp cornstarch

  • 4 tbsp water

  • 1 tsp glycerin

  • 1 tsp vinegar


Cornstarch Recipe:

Post-cook: Much more gelatinous than the base recipe. Stickiness much more than base recipe. Much more pasty than slimy. Does not hold when you spread but looks much more solid congealed. The stickiest of the recipes.

Cornstarch: Adds a more solid composite structure to the plastic. The cornstarch is definitely responsible for creating a more lattice like structural form that is distinctly different from the rest of the ingredient recipes.

After 6 hours of drying:

  • 3 tbsp cornstarch

  • 4 tbsp water

  • 1 tsp glycerin

  • 1 tsp vinegar


Water Recipe:

Post-cook: Gooey, lubricant like, more fluid than maple syrup. Silmey but does not hold together when spread. This is the  slimiest/slipperiest of the recipes.

Water: From our observations we had a hard time discerning the exact role of water in the plastic mixture. We did note that the mixture was much more lubricant like rather than goo like compared to the other recipes. If anything the water plays a mixer role in structural binding of the different components of the plastic, however an increase in water input impacts the characteristics of mixture and amplifies different characteristics of the glycerin more towards the slimier and slippery side rather than a stickier and gooier side.

  • 1 tbsp cornstarch

  • 12 tbsp water

  • 1 tsp glycerin

  • 1 tsp vinegar


Glycerin Recipe:

Post-cook: Similar characteristics to the base recipe but the viscosity and gooeyness is at a much higher level. It was not as sticky as the base recipe nor as slimy. This was definitely the most gooiest out of all the recipes. When we spread the plastic it held together the most as in the bonds of the plastic held when spread out between fingers.

Glycerin: From our observations the glycerin has a distinct impact in the recipe much like the cornstarch except the glycerin exacerbates the viscosity and stickiness of the plastic. Out of all the recipes the glycerin held the most form when spread apart. The glycerin held the most form after the cornstarch however the physical properties weren’t close to that of the lattice like starch structure and much more adjacent towards a polymer structure that has much fluidity and variance.

After 6 hours of drying:

  • 1 tbsp cornstarch

  • 4 tbsp water

  • 3 tsp glycerin

  • 1 tsp vinegar


Vinegar Recipe:

Post-cook: Similar to the glycerin in many ways however the difference between the two is that the plastic was much more fluid than the glycerin. The vinegar held together in the same fashion as the glycerin but it did not have the same form, the structure was more liquid like while the glycerin had a much more slime pasty structure.

Vinegar: The vinegar produced similar results to that of the glycerin however it was not as solid in the polymer structure as the glycerin, rather it was much more fluid like. The vinegar is much more of a mystery than the water. The distinct characteristic of the vinegar is that it is acidic in its property so its role may facilitate a reaction between the glycerin and starch. We can infer this because the bond of the plastic when spread apart was similar in strength to the glycerin however not as gooey, it had more fluid state.

  • 1 tbsp cornstarch

  • 4 tbsp water

  • 1 tsp glycerin

  • 3 tsp vinegar


 Coffee & Coco Recipe:




Questions & Further Inquiry:

  1. A more reductive approach in excluding singular inputs of the recipe.

  2. More formal testing in regards to quantitative measures rather than qualitative observations in the characteristics of the plastic.

  3. Additive testing, adding different adjacent components to create a different type of end plastic.

  4. How could we make a bio-resin filament for 3D print?

  5. Could these bioplastics replace standard glues? At least for housework and crafts?

After 24 hours of drying:

Starch recipe: Surface is completely dry, small air bubbles are trapped in the surface. the underneath of the plastic is still drying . It is possible to touch the plastic without mess on fingers. It has a matte texture and the small amount of cocoa that was added gives the plastic an appearance of orange.

Cocoa + coffee recipe: The plastic is the second driest of our list. This plastic is a notable brown and transparent color. Unlike the starch recipe, this appears to be still more of a gel than a paste.

The rest of the recipes: All the other recipes dry at about the same rate. They are still viscous, sticky, and have the appearance of glue.

After 36 hours of drying:

Base Recipe
Base Recipe


Coco & Coffee
Coco & Coffee

Starch recipe: Most of plastic is dry but remaining wet spots under the wax paper are still visible. Very matte and smooth texture, nice to touch and potentially a cool material to work with on tactile projects in the future.

Cocoa + coffee recipe: This recipe is still the second driest batch. It’s texture is still viscous but the surface is approaching a matte feel.

The rest of the recipes: These recipes are still viscous and “gooey”. Although when touching the “paste”, it sticks to the fingers but when stretched out far enough, will let go and spring back into itself, leaving the finger clean. This means that there is no more liquid attaching to the surface of the finger, the plastics have become more solid.