Can plastic water bottles be used for anything?

What might anything be? There are some things I would not want to put in a water bottle but that is my opinion.

how big are your water bottles?

yes cut in half use to start veg. or flier plants in. Or cut the top off as much as you want stick different wrapping paper around it and paint or spray lacquer, instinct vase. Cut a piece of 1x3, nail it to studs in shop or work area. Drill holes inside of bott wall and attach to the 1/3. Use to store nuts,bolts,etc. Hop this helps

You can cut the bottles in half. Use the top half with the cap as a mini greenhouse over seeds you have started.

Use the bottom half to hold water, paint or glazes from a larger can, or to mix colors in. 1/4 to 1/2 cup will be enough for touch ups, cleanups, or smaller tasks.

Best wishes ☺️