Plaster Section Model

A material experiment on whether casting long spanning voids between plaster is possible.

Step 1: 3D Modeling

Before we get to physical construction of the actual sections, we need to design a 3d model of what we want.

I chose to go with this basic design with 3 different slabs that overlap each other to some degree, this will give us ample space for the brass rods to sit and hold the slabs in place later when we cast everything together.

The model you see here was done in Rhino.

Step 2: Materials

Besides the computer, we'll need the following materials for this project:

-Plaster

-Hot Glue Gun

- 1/4" Foam Core

-Saw for metal

-Brass rods (or any other type of metal rods)

-Screw driver

-Xacto Cutter

Step 3: Cut Files

Through the 3D model that was constructed in Rhino, we are able to unroll the negatives of the model out into simple panels that we'll cut out to use as our guide when we cut the foam core.

Step 4: Cutting the Foam Core

After we have the panels printed and cut out, I suggest you lay the guide over a sheet of foam core to obtain the foam core pieces that will be glued inside the mold.

These pieces will become the material you remove after the pour to become the negative space in the model.

Step 5: Constructing the Mold

After the more complicated pieces are cut out, we can cut out the actual mold of our cast. The cast will be sized 1.5"x3"x6".

To make a mold that creates that sized cast, the pieces should be cut so that they are a little longer than they are in order to hold in the plaster that will be poured in.

the pieces shown in the picture are sized:

2 pieces that are 3"x6.5"

2 pieces that are 3"x1.5"

and one base piece that can be any sized as long as it's larger than 2"x6.5"

Step 6: GLUE!

Glue the pieces that you've cut out together. I suggest you glue 3 of the edge pieces first and then continue with the pieces that will fit inside like the picture shows.

The interior dimensions should measure 1.5"x6" like mentioned in the previous step.

Step 7: Skewer Those Voids

After the mold is completed, take the rods and cut one end so that it is slightly sharp. This way piercing through the foam core should be a lot easier than with a blunt end.

While inserting the rods and cutting them to the right length so that they are flush with the mold itself, be sure that the rods are passing through at least 2 voids at a time at varying angles. These rods will act as support of the plaster after it's poured and the different angles will serve to hold everything in place so the individual pieces of plaster won't come sliding off.

Step 8: Water-tightening

After your rods have are in place and cut to length within the mold, to be careful to hot glue any open crevices or holes that may have been made during this process.

This step is crucial to ensuring that the pour comes out successful.

Step 9: Pour the Plaster

Mix plaster as instructed by the container that it comes in and fill the mold up with the plaster, just slightly over the top of the inside pieces of foam core.

Remember to tap the mold a few times on the table to remove any bubbles that may have been trapped inside.

Step 10: Wait and Remove

Let the plaster dry a decent amount (or instructed by the packaging) before removing the foam core mold.

The pieces between the plaster could be slightly harder to remove, so I suggest using a screwdriver to slowly work the foam core out from within.

After you've done so, your plaster section model is done!