[Radio Wrangler]

For this application, the size isn't very important.

If you were making an inductor to tune a resonance to a specific frequency, then the number of turns of wire and the exact core details would be important.

But for this purpose, you have found a core of a suitable material and of a reasonable size.

For the sort of interference suppression being discussed in this thread, you should begin with what is called a "Common-Mode Choke" which is wound with two wires. One carrying the supply voltage and one carrying the return path.

They are connected so that the current taken by the equipment down the supply wire creates a magnetic field which is cancelled by the current in the return conductor.

David