How to use:

1) hold an assembling machine item or ghost in your inventory (that is capable of barreling operations)
2) hover over something that has pipe connections active
3) clear your cursor (Q by default)
4) move your cursor to one of the white fluid squares (alt mode recommended)
5) pipette one of the white fluid squares
6) place your ghost down over an existing assembler or an entirely new one

At the time of writing 1.0.0 is in a "works well enough" state, some issues can be expected but will be fixed over time.