I've done the gift jars before, and they are a lot of fun. We used canning jars to put all the ingredients in, the kind with the metal ring and flat metal lid - what you would use to actually can with.
To decorate the tops, we took some velvety red material, plaid material and other Christmas print fabrics to create nice tops. We used the lid to measure out a larger circle of fabric, and cut the material out in circles using "pinking shears" which gave a zigzag edge to the fabric.
After you put all your ingredients in the jar, you put the metal inside lid down, then the fabric, then use the metal ring to hold the fabric in place. Then we put some ribbon tied around the top of the jar over the fabric, and added the recipe cards to the ribbon.
Turned out really nice!