i have cracked open many transformers to get to the wire after radio shaft stores clearance what's left of the stock supply of parts they used to sell/ it takes hours depending on the transformer and how its made
the iron plates don't have to be woven in in fact it could be an old chain link wound at both ends or cut in half to make winding easy then re attached somehow wind primary and secondary the to get the step up or down you need
many early transformers when first invented were solid iron with a detachable part for winding wire
but if the price is rite
31 years old now playing with crystal sets since 12 years old tweaking and tinkering and sharing ideas ever since...