Who was it who implemented an internal primary? Successfully, as I recall. I'm thinking of trying that but perhaps that someone, or someone else, would warn me off.
Ken Herrick
Ken,
Greg Leyh used an internal primary in his large Electrum project coil and it works well. The artist he worked with didn't want a visible primary. I think Greg used large copper tubing for his primary.
Cheers, John Freau