A case I designed (f3d included) for the BTT SKR V3 E3 with holes for a case for the TFT35 E3 here https://www.thingiverse.com/thing:4616410

Print the Fan Piece on the same print as the Top piece, it fits. Print that piece with 0 Top and Bottom and a grid infill if you want to mount a fan there. There is a 15mm distance between the centers of the two pieces, mess around til it works.