Be aware of anything that has a lot of air in it. The 2d stage of freezing also is in a vacuum. The air will greatly expand...and I mean GREATLY. A while back a friend said he loved freeze dried taffy and asked me do some. He unwrapped all the pieces for me but then left them in a hot car where they melted into a big lump. He sliced it up and we tried it. The slices were too thick and they swelled enough to clog up the whole thing. I had to dismantle the drying chamber to get it out. Luckily it dissolved readily in water so it wasn't bad to clean up.
Most ice cream dries ok but some brands seem to have lots of air whipped in. Those will expand a lot.
Speaking of ice cream - you know those Mtn House freeze dried ice cream sandwiches that sell for about $4 each? You can make your own for the price of the sandwiches, usually well under $1, plus the bag. Walmart sells some really cheap but you'll like the more expensive ice cream better.
