Bottle cap necklaces are a lot of fun to make and can be made quickly and easily for boys or girls or as a project with your children.
I wanted to make pendants that didn't require the use of power tools to drill or resin which I know some people are uncomfortable using.
There are a couple non-electric options for this. I used a push drill from American Science and Surplus for these, but have since switched to using a EuroTools plier punch(affiliate link). It costs a little bit for the basic tools and supplies but the glaze can do a lot of necklaces, and the punch and drill can be used over and over again.
You will need:
Bottle caps- I save the ones from the sodas my kids drink occasionally as well as asking local bartenders for caps
Headpins- I like using good quality headpins because they are less likely to break when I'm working with them.
Pliers- Round nose and chain nose
Something to pierce the bottle cap
Clear spray sealer if you're using an ink jet printer
Ranger Glossy Accents- you can pick this up at your local craft store, it's a dimensional paper glaze
1 inch circle punch- not really necessary, but it does make cutting out nice neat circles that fit in bottle caps perfectly very easy
Accents- Beads, glitter, confetti

Wash your bottle caps if necessary.
Drill a hole in your bottle cap where you want the top of the necklace to be. It takes a couple minutes using the hobby drill but it makes a nice small hole that worked well with the head pins I used. Slide the head pin through the hole and either put on a bead like I did with the pirate necklace for my daughter or just make a loop. You can find instructions for making wrapped loops here.
Print out your image or choose an image from a magazine or book, cut out a 1 inch circle. For the images in my example, I printed them in 300 ppi. Here is a template and the image for the dolphin necklace. Right click to save them to your hard drive and print them at 300 ppi. Spray them with the sealer to keep the ink from bleeding when you cover them with the glaze.

Put a little bit of the Glossy Accents in the bottom inside of the bottle cap and place your image on that. I went around the slightly ridged edge of the plastic inside my caps, if you buy bottle caps made for scrapbook embellishing, they will be just plain metal on the inside.
Cover the image with the glaze,making sure to seal the edges of the image very well, and add the embellishments you wish. The glaze is thick and will come out a bit milky but dries clear, you want a nice thick coat. I filled my caps about half way full. If you get air bubbles in your glaze, they can be pierced with a pin or drawn over to the side of the cap using a pin then popped.
For the pirate necklace, I used a gold ultra fine glitter, a black pearl and some crystals. For the dolphin necklace, I used just a touch of a crystal ultra fine glitter.
It takes about 12 hours for the glaze to cure completely.
These are a lot of fun to make with kids. If they are under 12 you may want to do the drilling and head pins, then let them do the rest to make friendship necklaces, necklaces of their favorite stars or book characters.
For the cord on the pirate necklace, I used a piece of opaque pantyhose. A one inch strip then I stretched it out once to cause it to curl up on itself. This makes a very stretchy cord that can go over heads easily, and you can get a lot of cords from one pair of pantyhose.
Just for fun, this is the cap I used for the pirate necklace. Sometimes caps you save off sodas can lend themselves to the designs you do, or you can use bottle caps from a special day or evening out.