Pot Core 18x11 + Bobbin 5x Sets Kits Magnetics F AL 160

However for split core transformers and inductors, a pot core is generally preferable A pot core bobbin bobbin-four-slots-coil

Maybe for only 20 watts you could make a 60Hz cut core or any dual bobbin arrangement work for

4×4 slot AET offers coil former, bobbin for ferrite pot cores P2616 to produce inductive components with effective magnetic shielding

4 masks of inca slot MMG India offer a wide range of 4 Slot Pot cores based on the old 'VlNKOR' series The cores are supplied gapped to an effective permeability range and are