The next part was assembling the (now 5) sections into a single huge (25kg) toroid. This was done with polyurethane glue, and since that requires water to make it 'go off', a contribution from the wifes sewing room with some polyester interfacing (as used in collars etc) to go between sections.
The polyester was cut to the same size as the core sections
and each one was dampened, glue spread on the two faces of the cores and it all clamped together in a stack
Next came the cable for the primary. My mate Andy, champion scrounger par excellence, has scored again!! First with the cores, then the 1.8mm coppper wire for the secondary and now with 13 m of 50 sq mm flexible welding cable for the primary. That's enough for mine and Andy's transformers which will require about 5.5m for the winding so leaves a bit for the tails!
Its double insulated (14.5 mm diameter) so the outer orange PVC will be removed (inner is 11.5 mm) to get the 12 turns into the toroid.