"Rats, I was afraid it was obvious and I was just missing something.  Since you opened this thread I hadn't been back to the Thingiverse site so missed that bit of goodness.

Thanks much!"

"Hi Brendan,

Looks like you've really got some momentum going with this project!  I have to admire your modeling skills, particularly since you're using SketchUp.  Very impressive.

I have a quick question about mounting the motors.  I've got my…"