Improving That Focuser on Baby

I ordered two 1" thick 2.5" OD aluminum discs from which to make larger diameter focus knobs.  After squaring the ends, I realized how much heavier they will make the focuser.  Twice the diameter means twice the weight,  which especially on such a small scope does horrible things to the balance.  I could drill lightening holes in the knobs with my 3/4" end mill, but a simpler, although less attractive solution hit me. A 2 1/2" acetal knob would be twice the volume of the stock knob, but acetal is half the density of aluminum.   All the mechanical properties that matter are about the same.   (Young's modulus is irrelevant in this application.)  I could even put 1" lightening holes in the acetal to reduce the weight even more, making it weigh less than stock.  It is also much faster to turn acetal than aluminum with less wear on the tools.