I designed this project to be an alternative. These "lights" don't use any source of power, and as long as they get some bright light during they day you'll get at least an hour of glow from them after dark. You can make the "bulbs" any shape and size, and design the length of the strand for the application. They require some effort up front, but can be blissfully ignored once installed.
The science involved here is the use of phosphorescent materials. Phosphors absorb light and slowly release it, creating the glowing effect. Technically, your bulbs will glow all of the time, but during the day it isn't very visible (they just look like pastel bits of plastic) and at night the glow starts out bright, but fades over time. More colors are becoming available all the time - I've used six different colors for my bulbs, instead of just the traditional green glow in the dark. I have found at least 11 different colors online, so you really do have a great number of options.
I did a bit of testing, and found that sunlight was the best for creating bright lights, but florescent and incandescent lights did a surprisingly good job of recharging the glow, too.
Step 1: Supplies and Equipment
-resin - this is Envirotext Light, an epoxy type resin is best for this project (I only used a tiny bit, you can buy a smaller package)
-phosphorescent/glow powders - available all over the internet, this site has a wide range
-string - nylon is my first choice for outdoor use, pretty much anything will hold up indoors
-drill, dremel, or other method of making holes in plastic - I used a 1/16th inch drill bit
-waxed paper or other surface protector
-dust mask - keep the powder out of your lungs
-safely glasses - keep flying bits of plastic out of your eyes
-gloves - disposable plastic for resin, leather for drilling your pieces
-mixing cups and stirring devices for your type of resin - I used waxed cups with volume markings and popsicle sticks, that won't work for all resins, check the instructions in your package
Step 2: Punch Your Pieces
Punch a piece of paper for each bulb. I used a 1 inch circle, but you can obviously make your bulbs whatever shape and size you want, and you can cut instead of punching. Make letters for a fancy happy birthday sign, hearts for valentine's day, morse code dots and dashes, whatever you want.
Punch or cut everything you plan to use ahead of time.
Step 3: Prepare Your Workspace
Place a penny on your surface, then a punched piece on top of it. The penny is there to keep the cardstock off the work surface. Make sure the penny is smaller than the cardstock piece, or find some other flat object to set each piece on. You want any extra resin to drip off the cardstock.
Arrange as many penny/cardstock stacks onto your work surface as you can without any touching. It's okay if you don't have the pennies and/or space for all of your bulbs - make some, let them harden, then make more.
Step 4: Mix the Resin
Envirotex is a two part resin that you mix in an equal 1:1 ratio. I used 10ml of each part (20ml total) and was able to cover 20-25 circles with that much resin.
Pour one part of your resin into the cup, up to whatever volume you're planning to use. Add some powder. I wasn't very scientific - I just put a generous layer of powder in. (If you're planning to make a bunch it would be wise to do some samples with weighed or measured powder and compare the effects.) Stir in the powder, then add the other part of your resin. Stir this together for one minute, making sure to periodically scrape down the sides.
*THIS IS IMPORTANT* Transfer the mixed resin into another container, and give it another stir. This is how you avoid having permanent "wet" spots on your finished pieces.
Step 5: Pour the Resin
After applying resin to 10 or so pieces, look back and first and assess if it needs a little more resin. If it's covered or close to covered, leave it alone. It it has large gaps add one drop, then check again in a bit.
Keep working. Resin will harden up surprisingly quickly at times.
Step 6: Leave It Alone
Breath on them until the bubbles are gone, then walk away. It will be pretty easy to tell when the job is done.
Leave the parts to set up for 24 hours. For real. JUST LEAVE THEM ALONE. All you can do now is ruin a good job.
Step 7: The Back of the Bulb
Once your bulbs are hardened, remove them from their support pennies. If drips of resin have stuck the pennies use a pair of pliers to pop the resin off. This works better when the resin is nor more than a few days old.
You have a decision to make at this point. If the string will be indoors and against something like a wall or the bulbs will be glued to something, they're done.
If the bulbs will be seen from both sides or used outdoors you'd better cover the back, too. You can use resin with the same color of glow powder for the brightest lights, resin with a white resin dye added to it to help with the color pop, or clear resin for the backing.
You can also add more layers for a thicker, more domed piece. Do a test - some resins layer very well and some don't.
Step 8: Drill the Holes
If you have a way to clamp the pieces use it. Otherwise wear leather gloves and keep your fingers away from the drill bit. Wear a dust mask to avoid inhaling dust and wear eye protection to keep bits of plastic shrapnel from blinding you.
Slowly drill each piece.
Brush off any dust immediately.
If you're planning to glue these to something you can (obviously) skip this step.
Step 9: String Them
Select the approximate point on the string where you want the bulb hanging.
Fold the string at that point.
Push the folded part of the string through the front of the bulb.
Bring that loop down and around the bottom of that bulb.
Continue adding bulbs until you have the light strand you want!
Step 10: Use Them!
The glow powder and resin combo has the potential to be useful in all sorts of situations. I know I would have loved to have some glowing nightlights when I was kid. Or, turn it around and make glowing eyes for the plush animals nightmares are made of.
If you make these take a picture and post it in the comments!