QRV since 1993.
You need a VNA to measure the final results and for tuningen of the coils.
First make a pick up coil for the vna to measure the resonance of a filter unit.
This is a coil of 3 turns Cu annealed wire with about 20mm diameter It is connected to a small size coax.
The value of the coil isn’t critical at all.
Isolate the coax/solder joins with tape to avoid DC contact to the coil under test.