The principle of a shrink cup are, the cup are cut from a fresh log and you put in a bottom made from dry wood. When the cup drys it will shrink and make a tight fit around the bottom. If your skilled enough you can make a cup that are watertight.
This is a easy and quickly made project. I'm using simple tools that most of you already have. My cup is made from birch but you can make it from any wood. It just needs to be fresh cut.
Step 1: Tools you need
Most will already have all the tools needed to make a cup. If you want to go very simple you can make it with only a saw, a knife and a hand drill.
But the marking gauge and the power drill makes it easier.
The ax, the froe and spookshave are used to make the bottom.
If you don't have a suitable knife look at my instructable showing how to make the perfect carving knifehttp://www.instructables.com/id/How-to-design-and-make-a-perfect-carving-knife/
Step 2: Getting the wood
I went into the forest and found a place with a lot of small birch trees. I have asked the owner and have got a permission to cut a small tree. From one tree you will get enough wood to make a lot of cups.
Step 3: The carving
Drill the holes before you cut it. That way it is easier to hold the wood, and you don't need a holding device.
Step 4: Carving the bottom ledge
The making of the bottom takes some patients and some skills. If you want to make a tight fit the ledge in the cup and the bottom needs to be very accurate. If you are skilled enough the cup will be watertight.
While you make the bottom store the cup in a plasticbag so it won't dry out while your working on the bottom. You can all so store it in a bucket of water. Just don't let it dry. If you want to wait to finish the cup you can store it in the freezer until you have the time to make the bottom.