A320

[jankees]

It varies.
If I have a good, hi-res image, I may use that.  For the Battlin Betty B-25 for instance I used a 600 dpi scan from a book.
In most cases, however, I draw them myself.
Sometimes I do it directly in Photoshop (if they are simple), but most of the times in Illustrator (like the tiger). You then get a vector image, and resizing those is no problem, and they will always be sharp.