After seeing what 123D Catch could do, and then catching a model of my own head, I decided that I needed to make my girlfriend a 3D printed locket with me in it. I figured that either she would find this endearing or laughably cheesy and sentimental (and - hence - endearing). When I gave it to her, she seemed to like it. I couldn't tell why, but I suspect it is the former reason.
For me, the tricky part about this was modeling the locket. I am by no means a stranger to 3D modeling; It is just that my skills are a little rusty. After teaching myself 3DS Max when I was 15, and then spending two full years of college doing 3D animation in Maya, I left the world of virtual 3D forms and did not look back. Over the years, all of the trauma was carefully purged from my head while I spent my time making real things. If I had known ten years ago that by making virtual things, you would some day be able to press a button and get a real thing in return, I may not have been so quick to flash my memory. Anyhow, while I may have been quite good at 3D modeling 10 years ago, I am currently in the process of relearning a lot of the skills. Fortunately, it is coming back rather quickly.
I am including two different sets of files. The first set is the 3-part locket in STL format for people without 3DS Max and who just want to figure this out on their own. The second set is the 3DS Max file that is set up such that it will be easy to import and insert your face into the locket. The following instructions will show you how to use the 3DS Max file to complete and export your own custom locket.
Step 1: Iterations
This locket went through a number of design iterations. The main problem was the hinge. The first two were too small and disintegrated when removing the build material. The third had tight tolerances and got fused... and then snapped. Same story with the fourth. I thought that if I made number 3 larger, the problem would resolve itself, but... nope. Finally, I got the hinge down just right. I reinforced the connection to the locket, increased the size of the rungs, and perfected the tolerances. I also added 2 extra rungs. You can see the difference between the two designs here.
Step 2: Catch Yourself
Sit perfectly still and get someone to take 15 - 30 pictures of you. Preferably, you should use a DSLR camera with a 35mm lens (or any lens set to 35mm) and a high F-stop. The goal is crisp, bright pictures, with everything in focus.
Download 123D Catch, load in your image sequence, and compute the photo scene.
If all goes well, you should have a 3D model of yourself. If not, start over from the beginning with no images.
Select and delete any weird bits that are protruding from yourself.
Finally, export it as a .obj file.
Step 3: Lift the Lid
Move the top part of the locket upwards along the Z-axis so that you can see inside the base.
Step 4: Import
Import your model.
Select the model and click on the modifier tab. Choose "Cap Holes" from the modifier list.
Scale and reposition it such that it sits nicely in the bottom part of the locket.
Step 5: Close the Lid
Put the top part of the locket back down such that it meets the bottom part.
Make sure that the 3D model of your face does not touch the underside of the top part of the locket. If it does, it will not close properly, and you should reposition/scale your face such that it can fit.
Step 6: Boolean
Select your face and open the compound object menu.
Select "Subtract (A - B)" and click "Pick Operand B."
Click on the large box.
If all goes well, you should be left with a bust of your head that fits perfectly within the locket.
Step 7: Rotate the Lid
Rotate the top of the lid 180 degrees along the X-axis.
The hinge attached to top of the lid will no longer be aligned with the hinge's pin.
Move the lid until the hinge is centered upon the pin. Basically, the rungs from the top part of the hinge should be aligned with rungs of the bottom part of the hinge.
Step 8: Attach
Click on the bottom part of the locket and go to the modifier tab.
Edit mesh should already be in the modifier stack. Make sure it is selected.
Click on the "attach" button and then click on the face. It should change the locket to be the same color as the face.
Step 9: Export
There are three parts of this locket; the bottom, top and pin.
Select each part of the locket individually and export it as an STL.
Step 10: Fix the STLs
You can fix the STLs very easily using Netfabb.
Open each STL one by one and go through the following process:
1) Click on the red plus.
2) Click "automatic repair" at the bottom
3) Select the standard repair option
4) Click "Apply Repair"
5) It will ask if you want to "Remove old part?" Click "yes"
6) Finally, go to "Part --> Export Part --> as STL"
7) If there are further problems, it will ask you to fix them. If prompted, click the button to repair fixes, wait for the green check, and click Export.
Step 11: 3D Print
Print it out of a solid material to ensure the hinge does not break. I used Objet's "ABS-like" plastic. It is much more structural than their standard Vero White.