I got my pre-ordered Trygon and decided I wanted options. So magnets were the answer. I have seen some other great magnetized Trygons since I did this one. I wanted to keep mine as simple as possible, and glue as many parts on as I can. I really don't like moving a model across the board and having parts fall off. I started magnetizing the head with a 6mm x1.5mm disc magnet. It is easier to mount the magnet into the neck piece BEFORE gluing the neck piece in. I drilled out the hole with a drill bit that matched my magnet size.
Next I drilled out the mounting spots for the mandible claws. I used a 1/8" x 1/32" disc magnet for this and drilled the holes with a 1/8" drill bit.
Then wedge some greenstuff in the center of the two holes to help hold the magnets and glue one on each side.
The picture above also shows how I insert the magnets. I put them on the end of my drill bit and then press them into the green stuff. Other methods end up with me inevitably on my hands and knees looking for a tiny little magnet in the carpet that has made a run for it.
Next I put one of the larger 6mm x 1.5mm disc magnets in the brain pan on top of a pile of greenstuff to hold on the different head armors. At this point, try on all the three different head armors to make sure the magnet or green stuff isn't in the way of the top of the head seating down all the way. I usually use superglue on top of the greenstuff and then mold the greenstuff around the edges of the magnet to make sure it stays in place.
Before putting the greenstuff in the head armor, try your nail head to make sure it is short enough for the armor to seat all the way down. When you are happy with the length of your nail, Put the greenstuff in the top of the head and push the head armor onto the lower head. I used some super glue between the nail and greenstuff again, molded it a little, and then pushed the head armor in place again.
At this point I reallized that the lower mandibles snapped into place pretty well and wouldn't need a magnet. Sure the prime has a different tongue, but I don't want to magnetize every piece. The mawloc tonge juts into the space between your magnets for the mandible claws, and so you need to try in the mawloc jaw to ensure it will fit when the green stuff sets up. Something like this.
Stay tuned for the next steps to keeping your options open for your Trygon/Prime/Mawloc.