As I had the parts all cut out, all I would need to do is clean up the edges with a bit of sand paper and chamfer the parts where needed to the appropriate angles (checking it against other parts of course). I still not have found any Weld 3 glue, so I have been using Revell Contacta Professional (from model store) to glue the parts instead. To keep the parts square, I have a good set square, and also some metal guides that hold the parts together till the glue sets. Sometimes a bit of tape has been useful to keep parts together.
Internal Rear Right and Internal Rear Left parts glued to the Head Base. Note chamfer on the Head Base.
Nose Supports glued onto the Head Mouth Face part.
Tape Guides glued for the ticker-tape tongue.
The other-side of the glued parts above, showing the mouth opening.
Rear Supports glued to Internal Rear Right and Internal Rear Left. I had to support the back of these to make sure the weight of them didn't change the internal angle between the internal parts and the Head Base.
You can see the supports clearly here.
Glue has cured and supports were removed.
The other view of the part.
Back Support glued into position against the Rear Supports. I used masking tape to hold the part in place till the glue cured.
While the glue was curing, I chamfered the Nose Face part and glued it against the Nose Supports and Head Moth Face. I used masking tape again to hold the part in place. Then I glued the base of the Head Mouth Face to Head Base. Supports were used to keep the part in place.
Another view of the parts glued.
View from above. With the light fading, I thought it was best to let the glue cure and strengthened over night.