Do you use a CPAP machine and are worried about what to do with all those big distilled water bottles? Here's a way to use some of them year after year. Cut a hole in the bottom roughly 2" x 3.5" (difficult to do but a wood burning tool or similar implement does the job in seconds - open a window first!). Cut off the entire top of the bottle down to where the straight sides begin. Poke four little holes (one on each side) an inch or so above what will be the bottom of the protector to insert garden staples through. Plant the seeds, or seedlings, put the protector in place and press the staples firmly into the ground. The hole in what was the bottom but is now the top will allow for air to circulate but will keep any varmints off. Gentle misting through the hole keeps the ground moist and creates humidity.
It does work and is not only a lot cheaper than buying such protectors from garden suppliers but keeps some of those big water bottles in use.