Recycling, reusing and re-purposing plus making something you need is great. I like this because I can have a jug with water and plant food plus one with just water. My old watering can developed a few holes (someone put a few pellets into it but no confession yet). All you need is: milk jug (or other plastic jug with cap) large needle lighter Use the lighter to heat the needle (gloves help save your fingers), poke needle though the lid (from the inside out). Heat the needle for each new hole. I got a little over zealous with the holes the first time so start with a few holes and then add more, if needed. I have seen posts of people using nails or a really small drill bit to put holes in the cap but the water stream could be to strong especially for seedlings, experiment to see what works for you. Milk jug caps are a softer plastic and easier to get the pin through but you can use water bottles or other plastic containers.
A really skinny brad or small nail chucked into a screw gun with 1/4" or so projecting can melt/gnaw it's way thru a plastic milk cap very quickly. Saves a lot of effort, and makes holes really fast. You may have to cut the head off with wirecutters. (Snip! It's ready!) A small nail or needle wired firmly on the business end of a soldering iron will also do the trick, if you don't mind a little smoke.
With larger holes it also isn't a bad "emergency" shower. 2 of them after they sat in the sun a while makes a decent sailor shower even with a short hair wash. Ice Tea or Simply Lemonade bottles actually work better.
I like that idea but is that a hand held shower? I am going to try that. I have to see how clean you can get from a milk jug shower.
Hand held works best, or it can be hung but it's harder to control. Wet yourself down by sprinkling thoroughly, put down the jug, lather up and then rinse off. Not the best shower you will ever have, but a lot better than nothing...and if there is sun, it will even be fairly warm.