poza

I used wood I had laying around. It's height is half it's length. So a 12 inch length would result in a 6 inch height and width.

I should add that the width was determined by the metal pipes I used as axles. I didn't want to cut the pipes (I'm lazy), so I cut the wood that makes the width of the base to match the pipes. I suspect it will be more likely to have a few Bic ink pens laying around that can be used for axles, so use them to determine the width.

This design could easily catapult an egg. The only modification might be to add a second rubber band to handle the extra weight of the egg.

I'm glad I'm not the only one who thought this was rather insensitive. I'm sure the author/maker had no ill intentions, and I certainly don't want to turn this into a political discussion, but this is poorly suited for the homeless. And for that matter, the author/maker probably had no intention of it being used by homeless. The professor in charge of this project, on the other hand is probably the insensitive one.

Concrete pipes ~may~ be cheap (i dunno really), but transporting and setting them in place isn't. This is a very creative and impressive build, but not suitable for the homeless.

The author used a US quarter. The US does not use a gold standard. That is, there is no supply of gold in ft Knox or anywhere else that your US money can be traded for. The US uses a "Fiat money" system.

It would be wise to use safety glasses.

Good point!