This (small) cool project, uses gravity to recycle unused water from one pot to another. I use it for my succulents (which don't require a whole lot of water), and it works perfect!
Step 1: Cut Out Egg Cartons
Using some sort of cutting tool, cut out each individual egg pocket.
Step 2: Poke Holes in Bottom of Each Pocket
Using a small (somewhat) sharp tool (a small phillips screwdriver works perfect) poke a hole into the bottom of each egg pocket.
Step 3: Attach Pockets
Using a needle and thread, loop thread through one corner, and then another thread through the opposite corner. At this point, the egg pockets will not be able to hang. Also make sure to leave plenty of extra thread.
Step 4: Superglue Strings in Place
This part is tricky. Make sure each egg pocket has about 3-4 inches of space between each other, and that strings connecting egg pockets are an equal length (so that the egg pocket will hang horizontally.)
Step 5: Cover Holes With Cloth
Cover each hole, that you created earlier, with a small piece cloth (the cloth should easily be able to lay flat in egg pocket.)
Step 6: Fill With Gravel
Fill each egg pocket to the top with gravel (sand works great too) and ensure that the cloth stays over the hole.
Step 7: Hang
Hang the contraption over the ground, and put some sort of cup (you can use an egg pocket) to catch the remaining water (which can be recycled.)