Filling audio rack tubes with sand, metal, grape nutz???

Excellent@mitch2 just ordered a bucket of metal!

I had a friend that poured a liquid gel type compound into the legs I think he got it from one of the hobby stores. they were dead to any taping and added a surprising amount of mass. of course there is no removing at that point your committed.  

There is a product that is used to solidify latex paint for disposal. You might be able to use that with a couple quarts of inexpensive or surplus latex paint. 

If you ordered the steel shot you will not have the same level of concern as with lead.  Of course, you can look to see if there is an MSDS for how to handle the material and if you want to be absolutely safe you can always fill and cap the stands outdoors so there is no residual dust in the house 😷 and then carry (or roll with a dolly) the stands into the house. Your biggest risk is to not hurt your back moving them around 🤕