Ah, ok. I'll try that also (assuming for more complex work).
Thanks for the quick followup! :D
Edit: no, the 3D thing won't work for this particular thing... the end result needs to be the exact same size/shape/corner-coordinates as the template image (these pieces go together like a jigsaw puzzle). I can do that with a 2D setup by just matching the corners of the fancy image over a template, but that won't work in 3D (the template is 2D). Will stick with 2D transforms for now, I think.