In this Instructable, I use 123D Catch to capture the complex, organic geometry of a bumpy pumpkin (or Bumpkin) from photographs.
Then, I bring the capture into Meshmixer to create a removable top piece that fits perfectly.
Finally, I 3D print out the top and carved out body in a transparent material, and place a LED inside for a stylish, glowing Halloween/Thanksgiving dinner table decoration.
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Step 1: Capture a Pumpkin With 123D Catch
For this project, I used the 123D Catch iPhone app to capture a unique, bumpy pumpkin I bought at the local pumpkin patch.
I shot about 20 photographs around the pumpkin from a low angle, then another 20 or so from the top down. I make sure to place it on a detailed surface and not to move it while shooting the photos.
More on shooting the best photos here: http://www.123dapp.com/howto/catch
You can see how I framed the pumpkin from above and below with the images below.
In the 123D Catch app, I clicked "Submit Photos" to start the upload and processing of my pumpkin capture.
After about a half hour, the capture was finished. On your phone, tap to view and publish your (now) 3D pumpkin! You can frame it up, add a name, then make it public or private.
Step 2: Import the Capture Into Meshmixer
I will use Meshmixer to heal the bottom of the capture and make a flat part on the bottom for the jack-o-lantern to rest on (when its printed out).
Meshmixer is a free app at 123dapp.com/meshmixer. It can do quite a bit for 3D printing, and here I use just a few tools for my purposes.
First, learn the how to navigate inside of Meshmixer:
Orbit: Alt + left click drag
Zoom: Alt + right click drag
Pan: Alt + scroll wheel click drag
Note: You can change the navigation controls to 123D if you want from the menu....View...Navigation Mode...123D.
1. When you launch the app, click 123D and browse to your finished capture in "My Projects" (it is all ready to go there since the capture was automagically saved to your 123D account).
2. You may press the "T" key to Transform your model right side up if it isn't (Also available in the "Edit" bucket).
3. Once upright, press the "A" key or click "Accept" for the reorientation
4. You may need to remove extraneous bits of geometry from the scene. You can use the select tool to lasso them then press delete. Try to isolate pumpkin part of the capture.
5. You can fix any mesh issues with the Inspector. Click Analysis, then Inspector. Press Auto repair all and then Done.
Step 3: Make the Capture Flat on the Bottom
Now lets use the plane cut tool to cut the bottom part of the pumpkin flat.
1. From the "Edit" bucket, choose "Plane Cut".
2. Orient the cutting plane as you want on the bottom.
3. Click "A" to Accept the plane cut.
The plane cut will create flat geometry where you cut the mesh.
Step 4: Hollow Out the Jack-o-lantern
Now we will hollow the pumpkin piece so that it will have a wall thickness.
1. Select the pumpkin by clicking on it (it should already be).
2. Choose Edit...Hollow.
3. You will see the hollowed out piece inside a transparent outershell. You can adjust the "Offset Distance" then click "Update Hollow" to make adjustments.
Note: you might want to make sure the hollow is thick enough to be able to cut the part in the next step. The scale of your object is arbitrary since we didn't set that up, so you can eyeball the thickness you want (knowing you will later print this at some scale your printer allows).
4. When you like the hollow thickness, click Accept.
Step 5: Cut Out the Top and Bottom Piece
I created a "cutout" piece in 123D Design that I will use to create the top piece and the void in the pumkin body for that matter.
It is simply two cylinders stacked on top of each other, the top one slightly larger in diameter (see image).
Its attached to this Instructable, or you can download it here:
I'm going to import this piece and duplicate it and the pumpkin so there are two of each. With the 2 pairs of pumpkins and top, I can create the top, then the body, and they will line up perfectly.
1. In Meshmixer, click Import and choose the file attached to this Instructable called "topCutout.stl".
2. Choose "Append" to add it to the scene with the pumpkin. (you may get a dialog asking if you want "Shift Position", which you can click "yes" to.
3. Press "T" to Transform the cutout piece into position. I want the cylinder overhang to create a circular shelf for the top piece to rest on, so I place it such that it below the pumpkin surface all the way around.
4. You can check the depth of the overlap with the transparency shader from the shader bucket. Just drag the transparency shader (to the right of the globe shader) onto the model and rotate around to check the edge of the cutout is where you want it. Drag the default shader (next to the plus) back onto the object when finished.
TIP: The Orthographic view can help to better position the cutout piece just below the surface of the pumpkin (view...Orthographic)
Now we will duplicate both objects and use those to make the top and jack-o-lantern as separate pieces. I find it easiest to use the Object Browser to keep things in order.
5. From the menu, click "View...Show Objects Browser".
6. You can activate an object by clicking it in the Objects Browser. Try it! The active object is bright and the inactive object is dim. Select the cutoutPiece object to activate it. From the "Edit" bucket, choose "Duplicate" (or select the object in the Object Browser and press the Duplicate icon at the bottom of the Object Browser).
7. Double click the new duplicate cutout piece in the Objects Browser and rename it to "cutoutPiece".
8. Select the pumpkin capture and repeat "Duplicate" from the "Edit" bucket. Rename it to "pumpkinTop".
You now have two of each. Note that you can turn off the visibility of each object in the Objects Browser. Turn off the visibility of one pair of objects and make the pumpkin top.
9. Click the eyeball toggle in the Objects Browser to turn off visibility of the two objects we wont use. Make sure we are only looking at the two objects we just duplicated, "CutoutTop" and "Top".
10. Now, select one then the other while pressing the "Shift" button to multiselect both. (see screenshot)
11. From the "Edit" bucket, choose "Boolean Intersection".
12. Finally, press "A" or click Accept.
You now have your pumpkin top. Now do similar to cut out the top from the bottom using "Boolean Difference".
13. Turn off the visibility of the new top and on the visibility of the other two objects.
14. Select first the pumpkin, then shift select the cutout top piece in the Objects Browser and from the Edit bucket, choose "Boolean Difference".
15. Then, press "A" or click Accept.
You should have two objects in the Objects Browser now, a top and bottom perfectly aligned.
Next we'll hollow out the jack-o-lantern.
Step 6: Print It!
Either you may want to print this yourself on your own printer or use one of the 3D printing service providers built into Meshmixer.
1. Click "Print"
2. Either set up your own 3D printer layout, or choose one of the service providers from the dropdown list (3D hubs, Sculpteo, Shapeways, or imaterialise). Find a material that is translucent so the light can shine through.
I used the vero clear material on our Objet Connex 500 3D printer we have at the Autodesk office at Pier 9.
Have fun, Happy Halloween!