look at constraint but only in the X or Y etc

 

There's a Look At Constraint, in the Constraints tab, however if you only want this aim to work on the X, or maybe just the Y, you have to dig into the constraint, then go to the Common Tab (see top screenshot) and then only specify the rx or ry in the scope.

Remember to use Nulls to set custom pivots etc, then parent your desired geometry to the null.

@scale

 I can't believe I've never used @scale....

@pscale is useful for uniformly scaling the instance/copied object onto a point. But what if you need to adjust the scale on a per-axis basis?

@scale=set(1,2,3);

this will scale the object by 2 in the Y, and 3 in the Z

woop woop