Fill them up. CrazyBlue is right, those stands will resonate quite a bit if you leave them hollow...
Keep in mind, also, that because of their size and composition you are introducing two large, very reflective objects into your listening room. They do look very nice, but there is a reason that most stands are slim poles with a minimum of reflective surfaces.
I'm going to stain them the same colour as my previous stands, its the same stain as my dyi bookcase and soon to be coffee table.
So I have a question? if I fill the stands with sand do I fill the whole column up? I'm going to take Crazyblues advice and use the quartz sand.
Thank you very much. I really liked the way these stands turned out but they just didn't seem to fit right with the speakers, don't know if the speakers where to big?
I find the imaging to be a little better with them being several inches higher. plus the column looks a lot better suited to these speakers, hopefully I can finish the sanding and base plates this weekend.
Just thought I would show the bookcase/DVD rack that I made prior to the speaker stands. It was the first project I made for my house, I'm going to use the same colour stain on my speaker stands.