About this 3D model
http://open-source-energy.org/ This is a single design, as in the inductors / primary&secondary are in different cores. The gap is adjustable on the core using the thumb screws on the top there are set screws holding the core's in place. Files are also Here: http://open-source-energy.org/files/rwg42985/russ/Projects/Stanly%20A.%20Meyer/A.R%20VIC%20Bobbin%20Single%20-%20Adjustable/ Watch this video for more info https://www.youtube.com/watch?v=k_P_8b6BLpw