Makin's Clay has several great molds that work well with resin and jewelry clay!
Check out their products here: http://www.makinsclay.com/products/push_mold.php
Trinket Foundry has awesome tumbled glass pieces for jewelry.
Check out all the have to offer here: http://www.trinketfoundry.com/index.php?p=home
For the snowflake in the middle I am using some Amazing Casting Resin.
This variety of resin hardens completely in 10 minutes and sets to opaque white.
I'm also using Alumilite Pearlescent Powder by the same makers of Amazing Casting Resin.
Spray the mold with mold release and let it dry.
Brush the mold with the Pearlescent Powder.
Mix up a batch of Amazing Casting Resin and fill the mold.
Let this set for 10 minutes to harden.
Only 10 minutes and you have some sparkly snowflakes!
Seal the glass piece to some contact paper to create a backing.
Mix up a batch of EasyCast Resin and fill the glass piece about halfway.
Add your snowflake and sequins and finish filling the piece.
Let set for 24-72 hours to harden.
To make this hangable you'll need E-6000 and a bail.
Attach the bail to the back of the piece with the E-6000 and let set for 24 hours to reach maximum adhesion.
The bail I'm using is a Silver Medium Leaf Bail from Aanraku Glass Studios.
They make wonderful metal pieces that work great with resin.
Check out all they offer here: http://store.abasg.com/mm5/merchant.mvc
Add to a chain for a necklace or a ribbon to hang on the tree!