Ferrite: Pot Core - (ICH) B65943A-X22 Pic 47 mm 29.8 mm

http://www.surplussales.com/Inductors/FerPotC/FerPotC-1.html

3D .stl file for bobbin:

http://laserhacker.com/3DParts/BoibbinSJRLooper.STL