Little note of caution;
My fancy tray (walk in) started to almost overflow after about 3 months. I was thinking oh shit, the whole lot will have to be re-done. The drain hole wasn't a 'hole' as such and i could see no way of unblocking it. Didn't wanna start trying to pull the thing out as it looked attached to the tray.
Rang the fitter and he said 'just pull the little cup straight out and the drain holes are underneath'. No prising out with blunt chisel or screwdriver or special tool. did what he said and bingo, the 'cup' lifted out and half the wife and grandaughters hair was caught in the trap. Pulled it out then put soda and vinegar down to clear it completely.
Not like the old days when a straightened coat-hanger would do the job..