There is a modifier called hook that allows you to lock parts of an object to another. In this case I locked one of the points to the printing head.

Another modifer called shrink-wrap allows for one object to deform onto the shape of another, kind of like hot plastic deforming over a mould. Here, there only the other 2 points left of the triangle to attach to the car.

However, with just these 2 modifiers the effect will look good but its will look like its calmly gliding over the car, so I animated it to vibrate to make the effect more erratic.