ok, so it is possible to make a diy freeze dryer. all that is needed is a vaccum chamber, freezer, and a cold trap to protect the pump from moisture. set your sample in your vaccum chamber and place the entire thing inside the freezer, after an hour or so once everything is frozen turn on your pump. The pump will run constantly for 24-35 hours depending on the amount of stuff you froze and the water content it has. Around the 24 hour mark the freezer temp can be left to drift to room temp by unplugging it. most of the moisture will be gone by this point, warming up ensures the last little bits will get removed. If your freeze drying useing dessicants is unnesserry. 
this is your other option, you can pull a vaccum on this and fill with dessicants and leave at room temp, although it’s not freeze dryed it would
be vaccum dessicated.
pictures courtasy of google!