We are investigaing trafos that can be bought as well as the DIY trafos. See the photos of all the tested trafos so far. 

Currently considered trafos are

Wurth CURR SENSE XFMR 1:750 40A SMD
https://www.digikey.com/en/products/detail/w%C3%BCrth-elektronik/7492540750/14617535?s=N4IgTCBcDaIOwBYCcYCsCAMdUZAXQF8g

Wurth XFMR FLYBACK AC/DC CONV 1.6MH TH
https://www.digikey.com/en/products/detail/w%C3%BCrth-elektronik/750341689/3992735

Power Tran. WE-UNIT Offline 175uH .85A 26Ohm 
https://eu.mouser.com/ProductDetail/Wurth-Elektronik/749118205?qs=AXuZnX5ayYSjlaXcMUJyIA%3D%3D

AUDIO XFMR 1.6KCT / 3.2 TH
https://www.digikey.com/en/products/detail/tamura/MET-23/285665

Flyback Transformers 230V/6V
https://eu.mouser.com/ProductDetail/Bourns/094931?qs=1Kr7Jg1SGW9TsHJ0%2FeggYQ%3D%3D

MYRRA 44301 230V/6V 16VA
https://export.farnell.com/myrra/44301/transformer-16va-6v/dp/1689092

MYRRA 44121 230V/6V 2VA
https://export.farnell.com/myrra/44121/transformer-2va-6v/dp/1689053

MYRRA 44163 230V/ 2x6V 3.2VA	kom
https://export.farnell.com/myrra/44163/transformer-2-3va-230v-2-x-6v/dp/1214587

as well as custom made trafos using cores (and corresponding coil formers)

ETD49/25/16 N87AL 3800NH
https://eu.mouser.com/ProductDetail/EPCOS-TDK/B66367GX187?qs=wDNl1cNI0GsHvw8cOBvW9w%3D%3D

95 ETD Core ETD29 Ind 2900 nH 25% TOL
https://eu.mouser.com/ProductDetail/Fair-Rite/9595293202?qs=FPho67LvealS12h1UIWe2A%3D%3D

E20/10/6 N30
https://eu.mouser.com/ProductDetail/EPCOS-TDK/B66311G0000X130?qs=%2FsLciWRBLmASyA8%252B9RDdOA%3D%3D

with wires 
AWG14 / 1.67mm dia., 5690V HY, 54m
AWG18 / 1.02mm dia., 5130V HY, 137m
AWG24 / 0.51mm dia., 4400V HY, 549m
AWG34 / 0.16mm dia., 2630V HY, 2220m