2C39

For my experiment I need 8 hot cathodes with grids in front of them to control the current.
Got 10 2C39 tubes on marktplaats.nl, the idea was to cut them open and use the filament, cathode and grid as a controllable source of electrons.
But... I found that the white ceramic material could contain beryllium oxide! Not a good idea to cut it, small beryllium oxide particles can be very toxic.
Maybe it is possible to cut the metal (the grid connection), I don't know if there is any ceramic material under the grid connection.