This stoppered jar shifts when shaken, as if full of a sand. It weighs approximately 2 pounds. 

You can use an action to remove the stopper, which remains attached to the bottle, whereupon a slow trickle of sand begins to trickle over the lip, like a pot of water slowly boiling over. When tipped to the side, the trickle grows faster in increments until tipped entirely upside down, whereupon it produces sand at a rate of 1 cup of sand per second. This flow is infinite.

As an action, a person holding or touching the jar can speak a command word to produce a powerful jet of sand with an initial exceptionally powerful burst, and then a constant jet that leaves the jar at a rate of 10 litres per second for one minute. 

When the command word is spoken, the initial burst creates such force, that if someone of size medium or smaller is holding the jar, they must succeed on a DC 15 strength saving throw or be pushed 15 feet in a direction reverse to the jet. If this momentum pushes the person into a solid or mostly solid surface, they take 3d6 bludgeoning damage.

If the jet is aimed at a creature of medium or smaller size, that creature must make a DC 15 strength saving throw or be pushed back 15 feet and take 3d6 bludgeoning damage. If they succeed on the saving throw, they are not pushed back, and take half as much damage. A tiny creature automatically fails the saving throw.

This torrent of sand can be stopped before the minute is up by putting the stopper back in the jar. This requires the person to pass a DC 10 strength check. 

Once used, this feature cannot be used again until the next dawn, though the jar will continue to produce sand at the slower rate ad infitum. 

Notes: Damage: Bludgeoning, Creation, Damage, Utility