To freeze-dry food at home, purchase a freeze-drying machine, or use a method that involves your freezer and makeshift drying trays. You can even experiment with dry ice. You need Mylar bags and a vacuum sealer for storage of the food to create a do-it-yourself freeze-dryer.
Harvest Right sells an in-home freeze-dryer that only requires the same amount of energy used by most other large kitchen appliances. Many of its models are under $4,000, as of 2015. The Harvest Right website provides great how-to videos.
To duplicate the freeze-drying process at home, use disposable roasting tins and your freezer. This drying process takes several weeks and works best with produce. Create a screen with your tins by making holes with a sharp object. Prepare your food, arrange similar food items on each tray, replace the lid, and layer the trays in a freezer set to the maximum temperature. Leave the trays for a minimum of three weeks, checking them regularly. Once the food has reached satisfactory dryness, store it in the proper bags.
You can also freeze-dry food using dry ice in a cooler that has been modified for the gas and that allows moisture to escape. Layer your freezer-bagged food in between layers of dry ice for up to 24 hours until it is hard.