We strongly recommend that you get one axis with one motor working perfectly before going on to the next. That way if you fall behind, you will still have a working machine for the show. Reliability is everything. For a rehearsal, run your machine 10 times, disconnect and reconnect the battery, then run it five more times. If everything goes smoothly, you have a reasonable chance of success at the show.
Liquids are problematic.
They are hard to transport hard to hold without leaks and hard to replenish. Also, see the design rules for the maximum amount of liquid allowed. Remember that after the show is over, you must completely clean any mess you make. Remember that your machine might have to operate up to 50 times at the show. The cost of replacing the consumables is not counted against your bill of materials cost, but the cost of the first instance of the consumable is.