Now i would not do this, but i see this kind of stuff about often -
A load of random holes drilled in the sides.
The centre bored out, leaving the top intact.
Some low wattage led thing shoved up the centre.
If you want to go further, and dim the light some, you could try and cut the middle hole square (ie with flat sides) and slide up some old printed circuit boards, so the light shines through them, and then out through the holes.
Again, its not what i would do. I kind of like that stuff, kind of hate it, but if you like it, it could look in keeping with similar.
3x3 is tiny, but i guess it could still work in the right context.