Dune (again)

The ntheenth reading of Dune (I forget when I first read it, possibly no later than the late 1980s) reveals irritations that a younger me glossed over oblivious, like what is a paracompass and why does it have a battery that will drain and break and enough of a battery to mix with the spice and (spoilers?) stabilize a slope with so they can find the missing pack? Needs of the plot, probably; there are simpler compass designs. More glaring is that they can move a Duke, etc, across space so why not collect watery asteroids or move a whole swimming pool? Humans are mostly water, just whip up some transparent aluminum and whoops that's a different universe.