Summary

I use these spacers on my Crossfire when mounted the frame.

You need to print
8x 20.7mm (for arms)
2x 25.6mm (for tail)
4x 1.4mm (i use it to get some clearance between the power distribution board an the plastic part to prevent dust short circuit)

23/Feb/2014: Added 1.4mm spacer

Probably will add more types when i need them.

Crossfire 2: http://www.thingiverse.com/thing:234867