I now physically have the LEDs and lenses. 2 immediate problems, both
active faces of the lenses are dead flat. In the pdfs it looked as
though the front faces were surrounded in a ring and I assumed (pdfs not
clear pics) the 4 corner holes of the LEDs would mesh with pips on the
rear of the lens.
They are made for mounting to pcbs not the other way round, so no
provisions for that. So I have to find some 12mm or so diameter thinn
rings to align the front faces to my 5 inch cistern ball valve float as
spherical former, and make some sort of jig for aligning the LEds to the
lenses , plus fixing them together