With the prusa launch of the Full Spectrum colour mixing i thought Id upload my simple print for tool alignement. FS colour mixing equires exact tool alignment for stacking layers on top of each other. tiny variations will cause colour casts on one side or other of a print. tool 1 is the datum so printing one of these for each tool with a 1:1 mix (1212121212 pattern) will indicate a misalignment through one side of the peg being more or less tool 1 coloured. 

the point aligns in Y (to aid in diagnosis after) if the RIGHT side of the peg has more T2 Colour then adjust T2 X offset UP. if the LEFT side has more T2 Colour adjust offset DOWN

if BOTTOM (oposite point) has more T2 colour then adjust T2 Y offset UP. if BOTTOM has more T1 Colour then adjust T2 Offfset DOWN. if diagonal has more T2 colour then adjust each axis in its own way (top Right T2 Colour Move T2 X offset UP and Y Offfset DOWN)

you can itterate this- print takes about 20 mins. if it gets worse move the other way. this is more precise than the automated method and the vernier print method and is agnostic to nozzle debris and damage. Z Height offsets must alread have been auto calibrated. 

see photos for examples of colour casts nopth in a normal print and on the calibration peg