Beagle
speaking of which, i've sold some stuff on ebay lately and the fees have been unbelievable!
between them and paypal double dipping, I think they're getting about 20% to 25% of what I sold the items for!

No kidding!  I've had to resort to charging extra for shipping and handling to cover things.

I recently ordered some tungsten while working with my son to get his Pinewood derby car ready to race.  I found an online store that sold the supplies I needed that also had an ebay store.
 
The shipping if I ordered through their website was 7 bucks and $2.50 if I ordered through a bid on ebay.  Needless to say I bought it through ebay.

Was the tungsten part of the solar induction propulsion system you were installing in the paint matrix?

It's just about time for me to need more tungsten. 

hmmm tungsten

OK … this is the way my son explained it to me (he is 10):
 
The rules set a maximum weight of 5.0 ounces.  At weigh-in, they use a balance with a precision to the 1/10 of an ounce so, the car can weigh a maximum 5.045 ounces.
 
The race itself is a simple gravity race or in other words, all of the energy the car will possesses during the race comes while it is accelerating down the ramp and at least to a first approximation, all the cars will accelerate equally under the force of gravity.  The weight of the car comes into play while the cars are decelerating on the flat portion of the track (i.e., momentum is a function of mass).
 
Tungsten has a density of 19.25 g/cm^3.  The other alternatives are lead (far easier and cheaper to work with but discouraged) and gold.  By incorporating tungsten in the design, you are able to streamline the car and get the center of gravity fairly close to the rear axles.  The car is 7” long and by getting the center of gravity towards the rear of the car, you essentially maximize the amount of time the mass is “falling” (falling is in quotes) before it hits the flat track (a good thing).
 
Maximizing the weigh is only part of pinewood derby car optimization.  For example, friction is more complicated ... involving optimization of the axles and wheels and aligning the car … and is probably more important.
 
My son took a 1^st at the Pack level amongst the WEBELOS, 2^nd at the District level and 10^th at the Council level (at the Council 1st through 10th are trophy places and the difference in time between 1st and 10th is about 2/10's to 3/10th's of a second).  We were very happy because we have only been competing for 2 years here in MN.  When we raced our first 2 years in NJ, the rules were VERY different so, the approach to building a fast car was quite different.  The Pinewood Derby is kinda’ like the Free Masons, people who build fast cars are very secretive, once you get beyond the obvious; you have to figure it out on your own.  Also, folks out here in the Midwest take this very seriously, to the extent that some of the parents have tracks in their houses (the tracks are aluminum and can cost several thousand dollars) … we used a piece of Masonite to tune our car.

 
Awesome!
 
Thanks... I had a vicarious flash back to my youth.
 
Thanks for explaining.
 
best,
mike

quantumeffect
Tungsten has a density of 19.25 g/cm^3.  

Your 10 year old son knows THIS???!!!!????
 
I wanna party with him.

My density is somewhat higher.