Hi people,

In this instructable I'm going to explain how to make a plaster cast from a 3D computer model, using laser cut technology. I used corrugated cardboard to create a cool surface finish. Other materials such as plastics and wood can also be used (though this might make it impossible to remove your cast from the mold).

Note that some knowledge is required:
-Basic rhino skills ( Commands: Rectangle, Circle, Mesh Boolean Difference)

-how to make plaster ( https://www.instructables.com/id/Mixing-Plaster/ )

-how to operate a laser cutting machine (machine specific, ask the machine owner ;) )
-Rhino nest slice ( https://www.youtube.com/watch?v=HjwxKExhfzU)

Materials:

-Corrugated cardboard

-Plaster

-Water

-Fiber

Tools:
-Laser cutter

-bowls for the plaster

-Compressed air for cleaning (optional)

Software:

-Rhino

-RhinoNest

Goog luck and feel free to post your questions!

p.s.

This is my first instructable, so let me know if things are unclear ;)

Step 1: Choose Your Model

First thing is deciding which model you want to cast, and opening it in Rhino.

There are millions of different ways to make 3D models, so please be create and decide yourself ;)
I use a 3D scan of my own head ^^

Step 2: Make the Mold

Using basic Rhino commands I made the mol for casting the following way:

1: Draw a square around your model.

2.Extrude the square so your model will be entirely inside the box.

3. Select both the box and the model, then use the command MeshBooleanDifference to create the negative of your model.

4. Optional: Create more shapes and use MeshBooleanDifference again to make your mold smaller. This will save you some material ;)

5 Optional: I created a couple of vertical holes in the mold. These make the stacking of the layers of cardboard easier later on.

Step 3: Slice Your Mold

Use rhino nest to slice your mold and prepare for the laser cutter.
If you don't now how to do this, please check this tutorial:

Pro tip:
Be careful with the layer height. Your cardboard might seem to be 1.5mm high. But if it's exactly 1.6, this will make a huge difference when you're going to stack 100 layers!

Step 4: Build the Mold!

If you took the effort the make the holes in the second step, you'll have a major advantage this step!
Carefully lay out your cuts.
Start stacking in the correct order. You can put some pins in the holes of the mold, so everything will stay in place.

Bonus: Because you are making a mold, you will also have the slices for the positive model at the same time! Pretty neat, right ;)

Pro tip:
If you cardboard is slightly bent because of some moist, you can use some glue while stacking. If not, than glue is not necessary.

Step 5: Casting Time!

First you're going to have to make some plaster.

Check this tutorial If you don't no how to do it:
https://www.instructables.com/id/Mixing-Plaster/
I didn't have a fancy drill, doing it with your had will also be fine ;)

I'm sorry I don't have better pictures of this step, so I'm just going to describe it.

1 Pour in a small amount of plaster in the mold while it's still really liquid.
2 While it's hardening, your can make some more plaster

3 Drench some fibers in the plaster en cover your mold (see example picture), after the first layer has set.

4 Either fill the mold or just leave it, depending on the size of your mold. The 15cm tall head I made is completely solid.

Step 6: Unboxing & Cleaning

After about 2 hours the plaster will be hard.

You can peel off the layers of cardboard.
It might be hard, because the plaster will have penetrated the corrugated cardboard.

When you finished peeling off all the cardboard, you can clean your model with sponge, toothbrush, some water and pressured air.

Note: This is a lot of work. Please let me know if you have improvements for this step ;)