If you don't want to deal with resin but like secret wood pendants - I have a craft for you! You can combine hot glue with wood and it looks really cool :) You won't need any power tools and not even a glue gun. So let's start!

Supplies

hot glue sticks (stiffer glue sticks are better than more flexible ones)
craft knife (make sure it's sharp!)
candle
hair dryer
wire or eyepins
Optional:
watercolors or acrylic paints
felt tip pens, sharpies, fineliners...
clear nail polish
white glue

Step 1: Prepare Your Branch

First, get some branches from outside. That way you can make art with wood from special places :)

Break a branch in order to get some nice texture. I believe that "fresh" branches have a really nice texture, but any older branches will work too.

Then carve the bark of the tip away (unless you like to leave it).

Step 2: Optional: Paint the Wood

At this point you can stain or paint the wood with acrylic paints, watercolors or other paints.

Step 3: Melt Some Glue

Take a hot glue stick, cut a piece off of it and hold one end above a candle flame. You want it to melt really well until it almost starts dripping.

Then quickly push the branch inside the glue stick. It normally won't go very far though. That's where the hair dryer comes in: Use it to get the glue further down the branch and remove air bubbles.

I am not sure if this helps, but I put the glue into the fridge so it cooled down faster. I believe it makes the glue more transparent, but I couldn't confirm that hypothesis ;)

Step 4: Carve Away

When the glue has completely cooled down, you can take a cutting board and carve the glue with a craft knife into a crystal-like shape. This might require some practice and you need to be careful not to cut yourself, but a cutting board really helps.

When you are done, you can cut through the branch wherever you want the pendant to end. This will be easiest with a saw, but it works with a craft knife as well. The wood can be sanded for a nicer finish, but unfortunately you can't sand the hot glue.

Step 5: Making Pendants

In order to make pendants, I used two options:

Take a map tack and carefully make a hole. Then insert an eyepin with some superglue.
Make a groove with your knife and use it to wire wrap your pendant.

Step 6: Varnish

What really gives your crystal its transparency is some varnish. I used clear nail polish, but white glue works as well.

Step 7: Optional: Add Some Color

You can also decide what color you want your crystal to have. Just use literally any kind of marker, fineliner, sharpie or whatever you have and paint the crystal.

Next, take any white glue and brush it on. It will dry clear and look great!

Just be aware that lighter colors are more transparent and darker colours can hide some of the nice details inside the crystal.

Hope you like this idea and have a nice day! :)