For example, I'd be happy to devote some of my time to create a polymer clay model, since I have the material around anyway, but also paying for the postage stamps would put some strain on me (after all, we don't all live in the same country, and I don't really want to know what a small package to the US costs...).
This is my main problem with the giveaway idea (which I otherwise really like). I have, for example, a number of books we could giveaway. But if someone outside the US won one, it would cost more to mail the book to them than the book is probably worth. This is for mailing to Europe or Japan. The costs to Australia, New Zealand, Russia, and the like are even more. Mailing 2 or 3 books outside the US each month (at least to the more expensive countries) could cost as much as the server does for a month. We'd have to get a lot more donations just to cover postage.