I need to prototype an EI, EE, UI or similar core and I haven't been able to find a source in the USA that provides prototyping quantities of steel/iron transformer laminations.

I know there were sources long ago but I think they may have dried up.

For instance, magneticmetals.com just emailed me saying they discontinued doing that long ago.

Theres a guy on ebay selling laminated toroids but I need something I can wind a bobbin on (I'm using 2AWG solid copper).

Ideally I also need the associated bracketry that allows me to disassemble the transformer to remove the bobbin and change the windings while prototyping.

I know there are international sources but shipping around literally boxes of steel is going to be outrageously expensive.

Any ideas? Thanks for any help!