This tutorial describes how to create inserts for Pepakura objects that were printed off a little bit too small. As an example, the HD chest piece from Flying Squirrel will be adjusted to be a bit wider. Of course, it is always better to properly size a piece before you print it off and assemble it, but sometimes mistakes happen and if completely redoing the piece seems like too much work, adding inserts can be an acceptable alternative if you are not concerned with the most accurate of replica.
Here is what FS’s chest piece looks like initially and we will assume that the piece needs to be a bit wider to fit properly.
Copy down the Height dimension that you used when you printed off your ill-fitting piece.
The next step is to export the Pepakura file into the OBJ editable format using the file>export>3D OBJ File with UV Info command. You may need to have a licensed version of Pepakura to export OBJ files.
Next, open up the file in a 3D modeling program such as Blender which is freely downloadable from www.blender.org Other 3D programs will work as well, but this tutorial will use Blender. A fairly quick introduction to blender can be found at
http://www.youtube.com/watch?v=w-rDq6lEZAU
After opening up Blender, import the file using the File>Import>Wavefront(.obj) command as shown below.
After selecting import, the Pepakura file will open as an editable object as shown below.
At this point, you should to a test export of the object out of Blender as .obj file. The export command is right by the import command you used. The newly created .obj file can be opened by the Pepakura program and you should unfold the object. Copy down the “Scale” that is needed to give you the same dimensions as before. You will need this number later. Note that while the height is the same, the scale is different than before.
Inserts can be placed at any location in the model, but to help maintain the symmetry of the chest piece, the inserts in this example will be placed right down the middle of the piece. In order to slice the object in two, first you can create a box by pressing the space bar and selecting Add>Mesh>Cube. Move the cube so that it completely covers half of the chest piece, like the red chest piece is below.
Next, select the chest piece, and then while holding the shift key also select the box. While these two pieces are selected, using the menu in the lower left corner select Object>Boolean Operation>Difference. By performing this operation you will create an object like the green mesh that is a symmetrical half of the original chest piece.
You will need to edit the mesh so that the only vertices remaining are those that were flush with the box. You will also need to delete any faces that are a result of the support struts or were generated accidentally during the Boolean operation. To edit a mesh in Blender, select the object and press the Tab key. Then select the vertices that you wish to delete. In the picture below, the initial mesh is on the left while the cleaned up mesh is on the right.
Once you have an outline like show above, I recommend pressing “b” twice and using an area select on each point, and then pressing alt>m to merge any duplicate points. After the cross-section has been cleaned up so that each section consists of a continuous path of edges connected by edges, the cross section is extruded to form solid faces as shown below. To extrude the cross-section in Blender, select all of the vertices of the cross-section and press the “e” button. By dragging the newly generated vertices, you will be able to determine how much width you are going to add to the chest piece.
Once the cross section has been extruded, you will need to clean up the direction that the surfaces point, referred to as the surface normal. In Blender and other 3D modeling programs a surface is only exists in one direction and in order for the Pepakura program to properly recognize that two faces area connected, their surface normals must be aligned. For example, if 4 of the faces of a cube pointed inwards, and 2 of the faces of the cube pointed outwards, the Pepakura program would not recognize that the 4 faces are connected to the two faces. To better visualize which way the normals are facing, change the 3D drawing type to “textured” and make sure the “double sided” button is not checked for the faces as shown below:
In the viewer the back side of the normals will be transparent so it should be clear which way the surface normals are facing.
Once you have all the normals facing the proper direction, you can export the model as an .obj file using by selecting File>export>Wavefront(.obj). The obj file can be simply opened by the Pepakura program. If there are any extra objects in Blender other than the insert pieces, it is advisable to delete them before exporting to reduce the likelihood that the pepakura program will crash while opening the file.
Once the file is in Pepakura program, check to make sure that there are NOT yellow lines on the edges that should be connecting surfaces. If there are yellow lines such as shown below, go back to the Blender program and correct the model. Almost all of the problems indicated by yellow lines are caused by duplicate verticies/edges or normals facing the wrong way.
In order for the Pepakura program to draw those handy connector tabs, you will need to extrude the two edges that will be connecting the chest pieces as shown below and in some of the previous figures. It doesn’t matter how large the extrusion is since you won’t actually print them, but does help the extruded surfaces are moved at a bit of an angle to main insert pieces as shown below.
Once the final object is created in Blender, you can export it as a .obj file and open that file in the Pepakura program. Adjust the Pepakura model to the same “Scale” that you previously wrote down and unfold the model. Using the “Join/Disjoin Face” feature of Pepakura designer, separate all of the tab surfaces from the actual insert surfaces and using the “Edit Flaps” feature move all the flaps over to the insert surfaces. The tab pieces should moved to the gray area so that they are not printed. Your inserts should look something like the following when they are ready to print.
You can add the inserts to the chest piece by cutting the piece down the middle and then gluing in the inserts. The folds of the inserts should match up nearly perfectly with the original contour of the chest piece. The following is an example of an assembled FS chest piece with inserts in the middle of the chest and in the lower right and left sections that used to increase the width of the piece.
Since the model is now wider, the horizontal support struts will have to be lengthened as well, but those do not need to be as precise.
Here is what FS’s chest piece looks like initially and we will assume that the piece needs to be a bit wider to fit properly.
Copy down the Height dimension that you used when you printed off your ill-fitting piece.
The next step is to export the Pepakura file into the OBJ editable format using the file>export>3D OBJ File with UV Info command. You may need to have a licensed version of Pepakura to export OBJ files.
Next, open up the file in a 3D modeling program such as Blender which is freely downloadable from www.blender.org Other 3D programs will work as well, but this tutorial will use Blender. A fairly quick introduction to blender can be found at
http://www.youtube.com/watch?v=w-rDq6lEZAU
After opening up Blender, import the file using the File>Import>Wavefront(.obj) command as shown below.
After selecting import, the Pepakura file will open as an editable object as shown below.
At this point, you should to a test export of the object out of Blender as .obj file. The export command is right by the import command you used. The newly created .obj file can be opened by the Pepakura program and you should unfold the object. Copy down the “Scale” that is needed to give you the same dimensions as before. You will need this number later. Note that while the height is the same, the scale is different than before.
Inserts can be placed at any location in the model, but to help maintain the symmetry of the chest piece, the inserts in this example will be placed right down the middle of the piece. In order to slice the object in two, first you can create a box by pressing the space bar and selecting Add>Mesh>Cube. Move the cube so that it completely covers half of the chest piece, like the red chest piece is below.
Next, select the chest piece, and then while holding the shift key also select the box. While these two pieces are selected, using the menu in the lower left corner select Object>Boolean Operation>Difference. By performing this operation you will create an object like the green mesh that is a symmetrical half of the original chest piece.
You will need to edit the mesh so that the only vertices remaining are those that were flush with the box. You will also need to delete any faces that are a result of the support struts or were generated accidentally during the Boolean operation. To edit a mesh in Blender, select the object and press the Tab key. Then select the vertices that you wish to delete. In the picture below, the initial mesh is on the left while the cleaned up mesh is on the right.
Once you have an outline like show above, I recommend pressing “b” twice and using an area select on each point, and then pressing alt>m to merge any duplicate points. After the cross-section has been cleaned up so that each section consists of a continuous path of edges connected by edges, the cross section is extruded to form solid faces as shown below. To extrude the cross-section in Blender, select all of the vertices of the cross-section and press the “e” button. By dragging the newly generated vertices, you will be able to determine how much width you are going to add to the chest piece.
Once the cross section has been extruded, you will need to clean up the direction that the surfaces point, referred to as the surface normal. In Blender and other 3D modeling programs a surface is only exists in one direction and in order for the Pepakura program to properly recognize that two faces area connected, their surface normals must be aligned. For example, if 4 of the faces of a cube pointed inwards, and 2 of the faces of the cube pointed outwards, the Pepakura program would not recognize that the 4 faces are connected to the two faces. To better visualize which way the normals are facing, change the 3D drawing type to “textured” and make sure the “double sided” button is not checked for the faces as shown below:
In the viewer the back side of the normals will be transparent so it should be clear which way the surface normals are facing.
Once you have all the normals facing the proper direction, you can export the model as an .obj file using by selecting File>export>Wavefront(.obj). The obj file can be simply opened by the Pepakura program. If there are any extra objects in Blender other than the insert pieces, it is advisable to delete them before exporting to reduce the likelihood that the pepakura program will crash while opening the file.
Once the file is in Pepakura program, check to make sure that there are NOT yellow lines on the edges that should be connecting surfaces. If there are yellow lines such as shown below, go back to the Blender program and correct the model. Almost all of the problems indicated by yellow lines are caused by duplicate verticies/edges or normals facing the wrong way.
In order for the Pepakura program to draw those handy connector tabs, you will need to extrude the two edges that will be connecting the chest pieces as shown below and in some of the previous figures. It doesn’t matter how large the extrusion is since you won’t actually print them, but does help the extruded surfaces are moved at a bit of an angle to main insert pieces as shown below.
Once the final object is created in Blender, you can export it as a .obj file and open that file in the Pepakura program. Adjust the Pepakura model to the same “Scale” that you previously wrote down and unfold the model. Using the “Join/Disjoin Face” feature of Pepakura designer, separate all of the tab surfaces from the actual insert surfaces and using the “Edit Flaps” feature move all the flaps over to the insert surfaces. The tab pieces should moved to the gray area so that they are not printed. Your inserts should look something like the following when they are ready to print.
You can add the inserts to the chest piece by cutting the piece down the middle and then gluing in the inserts. The folds of the inserts should match up nearly perfectly with the original contour of the chest piece. The following is an example of an assembled FS chest piece with inserts in the middle of the chest and in the lower right and left sections that used to increase the width of the piece.
Since the model is now wider, the horizontal support struts will have to be lengthened as well, but those do not need to be as precise.
