One of the most annoying things about waterjets is they give you these tiny little hoppers, that barely hold maybe 80lbs of abrasive.. meaning you gotta stop it and fill it every couple hours. If you don't, you end up blasting abrasive everywhere and screwing up your cut. We researched large hopper options, but most companies wanted $5-8k for 500lb hopper. So we built our own, out of a $100 air tank off craigslist and some fittings.
Pathetic 80lb stock hopper:
$200 hopper we built from used air tank, and 3 pressure-proof viewing windows from grainger. We just cut off the top, flipped it, welded it back on, welded up a few (big -1 huge) holes, added a few fittings and wa-la. ~800lb capacity hopper. Thing even holds pressure - what do you know.