There was some discussion on the use of tungsten as a balance weight, so I did some research on the density of various materials - here is a list of approximate specific gravities:

Typical epoxy resin - 1.5

Aluminum - 2.6

Steel - 7.8

Lead - 11.3

tungsten - 19.2

It would appear that the higher density of tungsten would allow a more compact balance weight, allowing the weight to be more concentrated to the extremity of the available space, reducing the overall weight.  But things are not usually as simple as they at first seem.  In order for lead to be effectively used it has to be cast in a shape to fit the space, which is what I did.  It is hard to get all the air bubbles out, but a lead casting can be reasonably dense.  The tungsten, however must be used in the form of powder or rods held together by an epoxy matrix.  I don't have directly-related experience, but I would guess that it would be very difficult to get a 90% by volume tungsten mixture in epoxy (resulting specific gravity = 17.4) and if one was a little too casual and wanted to get an easily pourable mixture he could end up with a 50% mixture (specific gravity = 10.4), less dense than a lead casting.  With reasonable care, which means careful measuring of the epoxy and thoroughly mixing without trapping too much air I would guess a 70% mix is reasonable and 80% is possible, but not likely.  In comparison, rods perfectly nested in a linear pattern, not hexagonal, will be 78% "packed."  A 70% mix will yield a specific gravity of 13.9, 23% greater than lead.  Will that reduce the overall balancing weight by 23%?  No, because only part of that weight is at a small radius - the weight savings is more likely to be about 10% or less.  Is it worth the trouble?  It might be if an accurate lead casting is particularly difficult, but otherwise I doubt it - at least that was the reasoning when I decided to use lead.

Gary Casey