Our transformer is not computed, at least approximatively and core
bought. Windings must still be done! It's quite difficult for an
amateur to wind jointly turn on a rectangular core without special
equipment : you more likely have your windings done by a
professional. It's highly recommended to put transformers in a potting
after winding in order to suppress vibrations. The best procedure
involves covering windings with epoxy polymer (like araldite F) under
primary vacuum. Be careful not to include output connexions in plastic
during that operation!