Here is the process he followed from his project description:
- The dentist assesses your teeth for suitability for the procedure. Old-school bracket braces can move your teeth in basically any direction or rotation, but plastic aligners can only exert tipping / rotational forces on the teeth. When you put pressure on the crown of a tooth, the crown moves in that direction, and the root moves in the opposite direction (this is known as Begg’s tipping principle). Without being bonded to the tooth, plastic aligners also can’t do extrusion (pulling the tooth down and away from the maxillary arch).
- The teeth are 3D scanned. This used to be done by taking an impression, making a mold/casting, and then sending the cast to be accurately scanned. Now, there’s in-office tools like iTero that scan the teeth from within the mouth.
- The 3D model (usually an STL file) is taken into some proprietary orthodontic software, where the teeth are separated into separate objects. A technician plans out a route for the teeth to travel over the course of the procedure, so that they move but dont intersect one another.
- A series of models is created from the planned route, each representing a step in the motion.
- These models are 3D printed with high accuracy.
- Thermoplastic aligner material is vacuum formed over the 3D printed models.
- The plastic is manually trimmed away and the edges are smoothed, to create a non-irritating aligner.
For 3d printed part he used his own extensive modification of MendelMax 2 the "Minimal Mendel", but he writes that SLA machine would do a much better job.
You can see his work process in detail at:
DIY dentistry is not easy so you better think twice before trying it yourself.