Which left me with some nice parts to glue together using plastic weld
I weld the layers together, with a screw embedded, then bolt the top layer.
Screw/Bolt head Too Big
The bolt head is too big - forcing the sides out. I will just drop down to M1.6 screws, not M2 so that the head is ~3mm diameter.
Fingerprints in Weld
The welding of the parts has tell tale signs of a fingerprints, so I need to build a jig to hold them whilst welding.
Still they work as cufflinks
Now I just need to get the electronics working...