I think Amigakit has some 19" rack-mounted A1200s (and possibly other models too).
Is Motorollin' still around? He built a minimig(?) case out of lego iirc.
I used to have an A1200 mounted in a big Compaq desktop case (similar to G1200), but I created a much crappier aperture for the PCMCIA interface. Retired it when I got my first Power Tower.
Seem to remember someone mounting an Amiga inside a pizza box at some point also.
