Step 4: Seal in that LED Goodness
Get a decent silicone sealant that's suitable for outdoors applications. Get all of your bottles set upright and make sure you've got 1/4 to 1/2 inch of room above each of the paper towel plugs. Squeeze in some sealant, making sure to get plenty in amongst the bundle of wires. Allow to dry overnight and vacate the area, uncured silicone is nasty stuff!
When it's all done you should have a strong but flexible silicone plug at the top of each bottle.