The Mortar & Pestle is the first crafting station that you can acquire in Ark. It is used to process many raw resources into both final and useable items, and to produce resources used in advanced crafting.
Crafting with the Mortar & Pestle is quite similar to crafting from your inventory. The main difference is that it has its own inventory and can hold a lot more weight than most survivors.
To craft items and resources using the Mortar & Pestle you must first have the required Engram. Once you have that unlocked you will be able to find it in the Mortar & Pestle when you activate it. Adding and removing resources from the Mortar and Pestle is as simple as dragging and dropping, and holding shift while you are doing so will only move half the stack.
Once you have loaded your resources and selected your Engram you'll have crafting controls and a crafting queue at the bottom of the Mortar & Pestle interface that are almost identical to those you have when you craft from your inventory.
As far as bulk crafting goes, you don't have to keep the Mortar & Pestle inventory open once you have started a crafting process. Simply add your resources, setup your crafting queue, and then you can walk away. For example, you can set one up and then walk to another Mortar & Pestle where you can do the same thing. So far I've seen no limit to the number of Mortar & Pestles you can use. Just load them up and start the crafting.
On the Ark you have a few different crafting stations as well as the ability to craft in your inventory. You have to craft these items beforehand in order to use them, of course, but they provide you with advanced crafting options and allow you to craft even more Engrams. And unlike Inventory crafting, you can use many of these crafting stations at the same time.