Wow Lockzor, thanks for that post! I'm sure it could come in useful to people.
I think this thread would be a good addition to the tutorial forum, actually.
After quite a bit of searching in various places, I decided to buy this lightbox for $30 + $10 shipping:
http://www.save-on-crafts.com/artograph.htmlSome of the others I found were $200.
Way too much.
I hope to use it for illustration (inking drawings without having to go over the original pencil lines), and of course for animation. Would you believe that for the first animated film I tried to finish, I didn't have a lightbox (or a glass table) so I had to hold the paper up to the sunlight and draw that way? Really uncomfortable.
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One other thing: it helps to buy
thin sheets of paper, so that the light penetrates through more "frames". It's not easy to find, but it's out there. I think ideally, animation paper should have about the thickness of those packs of lined paper that they sell to schoolkids (but of course it should be blank, not lined). I think that's about twice as thin as "normal" paper.