Put fresh garlic cloves in food processor. I added some sea salt and processed on low speed until fairly smooth. It had the consistency of a slightly chunky mousse. Garlic mouse. 
Spread onto Teflon sheets and dehydrate at 125 degrees Fahrenheit until it has a crunchy crispy texture. Do not attempt to flip over, It will dry completely without flipping sides.
I gathered up the sides of the Teflon sheets to crumble the garlic towards the center. Next pour into jars with a few grains of rice to help prevent clumping. Do not pack it down; since there are no anti-caking agents your homemade garlic powder will turn into a hard sticky rock if it is packed or has even the slightest bit of moisture. Seal tightly and store in a cool dry place.
I don’t know how long this will last on the shelf but I’m going to find out.
Oh yeah, if you are going to dehydrate garlic you may want to do it outside. Unless you want every nook and cranny of your house to REEK of garlic. I do my garlic and onion dehydrating out in hubby’s shop.
Sustainable Living Cookbook 