First I wound the secondary on the PVC pipe with two-sided tape so the wire wouldn’t unwind. The whole winding is made by hand, I have a record for one in 3 days and for two in one week.
The number of windings is around 900 and thickness of the wire is 0.5 mm.
In the second picture there is the final product with the improvising primary winding and the second “receiver” coil.