Make Architecture



Assignment 6: Molding/Casting

This week for molding and casting I wanted to utilize the vacuum forming machine in an interesting way – using the blowing air function instead of the vacuum. This creates Isler-esque forms which I used to cast concrete bowls.

Creating the Mold:

To make the mold, I used the vacuum forming machine in the media lab, which heats up 1′ x 1′ sheets of  PET-G to a plastic state so it can be drawn down by the vacuum around an object. However, I used the vacuum release function to blow air up into the sheet to create a bubble.

I cut out an interesting shape in masonite to put over the plastic so that the bubble would form to that shape for the outside of the mold

This is the plastic in its heated-up state, ready to be “inflated”

For the inside of the mold, I used the same piece of masonite, but I wanted to put rib features in it – so I strung rubber bands across it to constrain the bubble

The first attempt at this failed because I overheated the plastic, so the bubble got too big, snapped a rubber band, then imploded

But after repairing the rubber band, I had success

This mold fit well into into the previous one (or so I thought)


I decided to use Rockite to mold with because it sets quickly, and would produce a strong and solid cast. I bought 5 pounds, because the next size up would be excessive. I thought I could get 2 casts out of it, the one I made the mold for before as well as a bigger bowl using a generic bubble I had made earlier and the exterior of the first cast as its interior (a casting sandwich)

I mixed the Rockite pretty thin so it would be easy to pour.

The mold required ~10 minutes of constant pressure before it set enough to keep its shape, otherwise the top piece started to float back up and the concrete pooled at the bottom of the mold. I left the masonite piece in there to give it a flat top surface.

This is the only other picture from the casting process – I got concrete all over my hands so I couldn’t take any more pictures.

The second bowl had problems because even though I poured all of my remaining Rockite – I did not have enough to fill the entire mold, so it is a much smaller bowl than I had expected

Releasing the  Casts:

Two issue plagued the first cast, both relating to the way the molds were made. The two pieces were not totally compatible, so when i put downward pressure the rim of the bowl became much thinner than the base

So the first thing that happened upon trying to get the cast out was the entire rim snapping off and crumbling

The second problem is that no matter how hard I try, I cannot get the cast out from the exterior mold. I think the way the rim took shape did not leave enough of a draft angle, and I do not want to use too much force for fear of breaking the cast, and the plastic is too thick to cut out with a utility knife.

The second mold came out easily. The plastic polished the surface coming out of the cast, giving it a very smooth and shiny surface.

Overall , my concept worked very well – the rockite releases very easily from the plastic and there are a tremenous number of possible shapes than can be cast in this way. I jut was not careful to ensure that the two molds worked well together in terms of thickness and that they were shaped to allow easy release.


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Instructor: Nick Gelpi TA: Skylar Tibbits TA: Varvara Toulkeridou
Class Times, Monday, 1-4pm - room 5-216
4.184 is an intensive introduction to methods of making explored through a wide range of brief but focused 1-week exercises. We'll engage the real and leave behind representation in the focused context of this class gaining skills for utilizing a range of fabrication machines and technologies from lasercutting, waterjet, 3D printing, welding, formworking-molding, casting, gears, joints and composites.
In this workshop we'll constrain ourselves to the territory of the 1:1. Students will represent architectural constructions at full scale and develop a more intimate relationship with technology by engaging the tools and techniques that empower us. We will gain access to the most cutting edge machines and technologies in the MARS lab at the Center for Bits and Atoms.
The second layer of information for this course will be to look at a series of case studies in which construction methods and technologies have played a dominant role in the design process .
Over the past 20 years, architects have focused on the technology of representation to create new ideas of what architecture could be. Looking back today, much of that research failed to substantially change the way we design buildings by focusing on apriori formal configurations. This class makes the contention that this failure comes from a lack of considerations of the potentials within fabrication knowledge. We look to the future of what building might become, given the expanded palette of personalize-able technologies available to us as architects. Students will participate in curious technological and material investigations, to discover the potentials, known and unknown, for these various technologies.
The sub-disciplines of what's drawn and what's built have been compartmentalized and disassociated as the representational tools of architecture have distanced themselves from the techniques of making. At the same time the technologies for “making” in architecture have provided us with new possibilities for reinventing how we translate into reality, the immaterial representations of architecture.


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