[chaoxu]

I wonder if one can hollow out the individual cubes to decrease the weight.

[lapetitejort]

Or you could increase the weight by using tungsten or depleted uranium.

[userbinator]

With the same dimensions as the one in the article, tungsten would be around 7.3lb, and DU is only slightly lighter. If it was osmium, the densest known element, it would be around 8.5lb.

[ncmncm]

Osmium would evaporate, slowly, and poison you while it did.

Strangely, osmium oxide is a gas.

Iridium might be the better choice.