Constructing 3D Models from 2D Materials

I’ve found this technique to be really useful for making quick, cheap mock-ups of 3D models, as well as getting some really interesting visual results for artmaking.

The first of the two main techniques I’ve been using is ‘slicing’ models in Rhino using the Contour command, then exporting the curves to Illustrator. The curves are cut out of flat material (usually cardboard or acrylic) on the laser cutter, then re-assembled with glue into a mock-up of the 3D model.

This technique results in an economical model relatively quickly, and allows you a lot of flexibility compared to ‘unfolding’ techniques such as those used with Pepakura. It can, however, be quite tedious to re-assemble all the slices in the proper order/orientation. It is also not the most accurate method, as the shape of the model depends on the orientation of our curves in Rhino matching the orientation of the cut slices.

I’ve written a couple of scripts that take a lot of the grunt-work out of processing files. They are free for you [and everyone] to use. Also, keep in mind that the laser cutter part of the equation is optional. The contours can be cut by hand, although it will be a much bigger pain in the ass.

Here is the basic technique:

In Rhino:

Create a 3D model in Rhino. It helps if the model is solid (aka a joined polysurface, aka watertight)
Create topological contour curves of the model using the Contour command. The contours can go in any direction, and the spacing should be equal to the depth of the material you’ll be using.
Group the curves: use the PlanarSrf command to create surfaces from each ‘level’ of slices. This accounts for contours which are donut-shaped, such as those that would come from a tube or bowl shape. These concentric curves must be grouped together to maintian the profile of the 3D model.
Flatten the surfaces: use the UnrollSrf command to align each surface to the top viewport. This will prevent the curves from being distorted upon export.
Convert back to curves: use the Make2D command to transform each surface back into the original curves. This prevents the need for extra editing once the curves are brought into Illustrator.
Export the curves as Illustrator files (*.ai). Preserve the scale, but since Illustrator does everything in points, convert to points (1 inch = 72 points). This will ensure the scale of the 3D model is preserved.

In Illustrator:

Open each curve file that we just exported from Rhino.
Move each curve or set of curves into its own layer in a file that has been templated for the laser cutter.
Arrange and format the curves, then send them to the laser cutter.

On the laser cutter:

Use the least amount of material possible.
Keep track of the pieces you’re cutting out. Numbers can be engraved by the laser cutter, or the cutouts can be kept in their original position and compared to the files.

In real life:

Assemble the slices, using numbers and/or Illustrator files and/or the Rhino model.
Bask in the glory.

The Scripts:

These scripts are distributed under a Creative Commons Attribution Noncommercial Share Alike 3.0 License. You must follow the terms of this license if you wish to use these scripts.

Please see http://creativecommons.org/licenses/by-nc-sa/3.0/ for details.

These scripts are not intended to do anything malicious, however I take no responsibility for any ill effects caused by these scripts.

Rhino:

'**************************************************
' This script takes a joined polysurface in Rhino 
' and cuts it up into flat sections, which are then
' exported as Illustrator paths. These paths can be 
' sent to a laser cutter and cut from flat material, 
' then glued together to form a mock-up of your 3D
' model. 
'
' The script creates a folder on the base of
' C:\ drive and exports the files there. A text file
' with the total number of contour curves is saved in
' the same directory.
'
' Cobbled together by Chris Reilly [creilly 4T saic D0T edu] in 2007. 
' This script is distributed under a Creative Commons
' Attribution-Noncommercial-Share Alike 3.0 License
' see http://creativecommons.org/licenses/by-nc-sa/3.0/ 
' for details
'**************************************************

Dim strObjects
Dim intCount
Dim strObj
Dim strCmd
Dim strFilenm
Dim strLayerName
Dim strLayerReturn
Dim strUserDefinedFolder
Dim objFileSys
Dim strNewFolder
Dim strNewPath
Dim objFSO
Dim objFolder
Dim strDirectory
Dim strTxtFile

'**************************************************

Sub createContours
	Rhino.Command "Contour"
	isolateObjectsToNewLayer("Working Surfaces")
End Sub

'**************************************************

Function isolateObjectsToNewLayer(strLayername)

	Rhino.AddLayer(strLayername)
	Rhino.Currentlayer(strLayername)
	Rhino.Command "ChangeToCurrentLayer"
	Rhino.Command "-OneLayerOn Enter" 

End Function

'**************************************************

Function exportCurves(strDirectory)

	intCount = 0

	Rhino.Command "SelNone"
	Rhino.Command "SelCrv"

	Rhino.Command "-SetActiveViewport Top"

	Rhino.Command "PlanarSrf Enter"

	Rhino.Command "SelNone"

	Rhino.Command "SelSrf"

	strObjects = Rhino.SelectedObjects()

	For Each strObj In strObjects

		Rhino.Command ("SelNone")

		strCmd = "SelID " &amp; strObj	
		Rhino.Command strCmd

		Rhino.Command "UnrollSrf Enter"
		Rhino.Command "SelNone"
		Rhino.Command "SelLast"
		Rhino.Command "-Make2D Enter"
		Rhino.Command "SelNone"
		Rhino.Command "SelLast"	

		strFilenm = strDirectory &amp; "\" &amp; intCount &amp; ".ai" 
		strCmd = "-Export " &amp; strFilenm &amp; " PreserveUnits=Yes,AIScale=72,Unit=points,RhinoScale=1 Enter"
		Rhino.Command strCmd 

		intCount = intCount + 1

	Next

	Set objFSO = CreateObject("Scripting.FileSystemObject")
	Set strTxtFile = objFSO.CreateTextFile(strDirectory &amp; "\" &amp; "Curve_Count.txt", vbTrue)

	intCrvCount = UBound(strObjects) + 1
	strTxtFile.WriteLine intCrvCount
	strTxtFile.Close

End Function

'*************************************************

Sub doEverything

	strLayerReturn = Rhino.CurrentLayer
	createContours	 

	strUserDefinedFolder = Rhino.GetString("Enter a name for the output folder (ALPHANUMERIC, NO SPACES)")
	strDirectory = "C:\" &amp; strUserDefinedFolder 
	Set objFSO = CreateObject("Scripting.FileSystemObject")

	If objFSO.FolderExists(strDirectory) Then
  		Set objFolder = objFSO.GetFolder(strDirectory)
 	  	WScript.Echo strDirectory &amp; " already created "
	Else
   		Set objFolder = objFSO.CreateFolder(strDirectory)
		msgbox "Illustrator curves will be exported to : " &amp; strDirectory
	End If

	exportCurves(strDirectory)
	Rhino.CurrentLayer strLayerReturn
	Rhino.Command "-OneLayerOn Enter" 

End Sub

'*************************************************

doEverything

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'**************************************************

' This script takes a joined polysurface in Rhino

' and cuts it up into flat sections, which are then

' exported as Illustrator paths. These paths can be

' sent to a laser cutter and cut from flat material,

' then glued together to form a mock-up of your 3D

' model.

' The script creates a folder on the base of

' C:\ drive and exports the files there. A text file

' with the total number of contour curves is saved in

' the same directory.

' Cobbled together by Chris Reilly [creilly 4T saic D0T edu] in 2007.

' This script is distributed under a Creative Commons

' Attribution-Noncommercial-Share Alike 3.0 License

' see http://creativecommons.org/licenses/by-nc-sa/3.0/

' for details

'**************************************************

Dim strObjects

Dim intCount

Dim strObj

Dim strCmd

Dim strFilenm

Dim strLayerName

Dim strLayerReturn

Dim strUserDefinedFolder

Dim objFileSys

Dim strNewFolder

Dim strNewPath

Dim objFSO

Dim objFolder

Dim strDirectory

Dim strTxtFile

'**************************************************

Sub createContours

Rhino.Command "Contour"

isolateObjectsToNewLayer("Working Surfaces")

End Sub

'**************************************************

Function isolateObjectsToNewLayer(strLayername)

Rhino.AddLayer(strLayername)

Rhino.Currentlayer(strLayername)

Rhino.Command "ChangeToCurrentLayer"

Rhino.Command "-OneLayerOn Enter"

End Function

'**************************************************

Function exportCurves(strDirectory)

intCount = 0

Rhino.Command "SelNone"

Rhino.Command "SelCrv"

Rhino.Command "-SetActiveViewport Top"

Rhino.Command "PlanarSrf Enter"

Rhino.Command "SelNone"

Rhino.Command "SelSrf"

strObjects = Rhino.SelectedObjects()

For Each strObj In strObjects

Rhino.Command ("SelNone")

strCmd = "SelID " & strObj

Rhino.Command strCmd

Rhino.Command "UnrollSrf Enter"

Rhino.Command "SelNone"

Rhino.Command "SelLast"

Rhino.Command "-Make2D Enter"

Rhino.Command "SelNone"

Rhino.Command "SelLast"

strFilenm = strDirectory & "\" & intCount & ".ai"

strCmd = "-Export " & strFilenm & " PreserveUnits=Yes,AIScale=72,Unit=points,RhinoScale=1 Enter"

Rhino.Command strCmd

intCount = intCount + 1

Set objFSO = CreateObject("Scripting.FileSystemObject")

Set strTxtFile = objFSO.CreateTextFile(strDirectory & "\" & "Curve_Count.txt", vbTrue)

intCrvCount = UBound(strObjects) + 1

strTxtFile.WriteLine intCrvCount

strTxtFile.Close

End Function

'*************************************************

Sub doEverything

strLayerReturn = Rhino.CurrentLayer

createContours

strUserDefinedFolder = Rhino.GetString("Enter a name for the output folder (ALPHANUMERIC, NO SPACES)")

strDirectory = "C:\" & strUserDefinedFolder

Set objFSO = CreateObject("Scripting.FileSystemObject")

If objFSO.FolderExists(strDirectory) Then

Set objFolder = objFSO.GetFolder(strDirectory)

WScript.Echo strDirectory & " already created "

Else

Set objFolder = objFSO.CreateFolder(strDirectory)

msgbox "Illustrator curves will be exported to : " & strDirectory

End If

exportCurves(strDirectory)

Rhino.CurrentLayer strLayerReturn

Rhino.Command "-OneLayerOn Enter"

End Sub

'*************************************************

doEverything

Illustrator:

This script works with a Rhino script to combine exported curves into 
one document. 


Cobbled together by Chris Reilly [creilly 4T saic D0T edu] in 2007. 

This script is distributed under a Creative Commons

Attribution-Noncommercial-Share Alike 3.0 License

see http://creativecommons.org/licenses/by-nc-sa/3.0/ for details
*/


// JavaScript Document

//read number of curves from 'Curve_Count.txt' which was output by Rhino. 
alert ("Select the file 'Curve_Count.txt'");
var textFilePath = File.openDialog("Select the file 'Curve_Count'");
var fileRef = new File(textFilePath);
fileRef.open("r");
var curveCount = fileRef.readln(0);

//locate and open the laser cutter template file
alert ("Select the laser cutter template file");
var templateFilePath = File.openDialog("Select the laser cutter template file");
var laserFile = new File(templateFilePath);
open (laserFile);

//cycle through the source curve files
for (var count = 0; count &lt; curveCount; count++) {
	
	var curvePath = new File (fileRef.parent + "/" + count + ".ai"); //the slash may have to be changed for Windows
	open (curvePath);//open the curve source file count.ai
	var curvePathConverted = curvePath.name.substr(0,(curvePath.name.length - 3)) + " [Converted].ai";
	doc = app.documents.getByName(curvePathConverted); //bring .ai to front. refer to as documents[1] since illustrator does a stupid renaming thing when opening the Rhino curves
	// = app.activeDocument; 
	
	//select all paths in curve source files and move to laser cutter template
	if ( doc.pathItems.length &gt; 0 ) { 
		
		//cycles through each pathitem in curve source file
		for ( i = doc.pathItems.length - 1; i &gt;= 0; i-- ) { 
			pathArt = doc.pathItems[i];  
			pathArt.selected = true; 
			
			var my_object = doc.pathItems[i];
			app.activeDocument = documents[laserFile.name];
			var destination_layer = app.activeDocument.layers["Layer " + parseFloat(count + 1)]; 
			my_object.move(destination_layer,ElementPlacement.PLACEATEND);
		} 
	} 
	
	//close the last curve source document w/o saving
	app.activeDocument = app.documents.getByName(curvePathConverted);
	aiDocument = app.activeDocument; 
	aiDocument.close( SaveOptions.DONOTSAVECHANGES ); 
	aiDocument = null; 
	
	//create the next layer in the laser cutter template
	app.activeDocument = documents[laserFile.name];
	app.activeDocument.layers.add();
	
}

This script works with a Rhino script to combine exported curves into

one document.

Cobbled together by Chris Reilly [creilly 4T saic D0T edu] in 2007.

This script is distributed under a Creative Commons

Attribution-Noncommercial-Share Alike 3.0 License

see http://creativecommons.org/licenses/by-nc-sa/3.0/ for details

// JavaScript Document

//read number of curves from 'Curve_Count.txt' which was output by Rhino.

alert ("Select the file 'Curve_Count.txt'");

var textFilePath = File.openDialog("Select the file 'Curve_Count'");

var fileRef = new File(textFilePath);

fileRef.open("r");

var curveCount = fileRef.readln(0);

//locate and open the laser cutter template file

alert ("Select the laser cutter template file");

var templateFilePath = File.openDialog("Select the laser cutter template file");

var laserFile = new File(templateFilePath);

open (laserFile);

//cycle through the source curve files

for (var count = 0; count < curveCount; count++) {

var curvePath = new File (fileRef.parent + "/" + count + ".ai"); //the slash may have to be changed for Windows

open (curvePath);//open the curve source file count.ai

var curvePathConverted = curvePath.name.substr(0,(curvePath.name.length - 3)) + " [Converted].ai";

doc = app.documents.getByName(curvePathConverted); //bring .ai to front. refer to as documents[1] since illustrator does a stupid renaming thing when opening the Rhino curves

// = app.activeDocument;

//select all paths in curve source files and move to laser cutter template

if ( doc.pathItems.length > 0 ) {

//cycles through each pathitem in curve source file

for ( i = doc.pathItems.length - 1; i >= 0; i-- ) {

pathArt = doc.pathItems[i];

pathArt.selected = true;

var my_object = doc.pathItems[i];

app.activeDocument = documents[laserFile.name];

var destination_layer = app.activeDocument.layers["Layer " + parseFloat(count + 1)];

my_object.move(destination_layer,ElementPlacement.PLACEATEND);

}

//close the last curve source document w/o saving

app.activeDocument = app.documents.getByName(curvePathConverted);

aiDocument = app.activeDocument;

aiDocument.close( SaveOptions.DONOTSAVECHANGES );

aiDocument = null;

//create the next layer in the laser cutter template

app.activeDocument = documents[laserFile.name];

app.activeDocument.layers.add();

}

Resources:

Update [2/7/2013]:

Since originally writing this post, some very useful plugins (namely Rhinonest) for Windows Rhino have come out that accomplish similar goals with more sophistication. Also, Rhino is working towards integrating Python scripting, which would allow for the OSX version to accomplish similar tasks as outlined here.

by Chris 18 years ago

Constructing 3D Models from 2D Materials

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