anet a6 - Z-Axis Laser Leveller

I'm mounting a laser pointer on my left z-axis housing, and a target on my right z-axis housing, so that I can easily see when they get out of alignment with each other.

The actual laser pointers are a buck each on ebay:
http://www.ebay.com.au/itm/1pcs-LED-Light-Laser-Pointer-Funny-Cat-Rod-Laser-pet-Cat-free-shipping-/112270606961?hash=item1a23d98271:g:RPQAAOSwZQRYfC~Z

This gives direct feedback when the two Z-axis steppers get out of sync with each other - which happens surprisingly o