Wipe down your tray with a damp cloth and make sure it's clean.
Apply a thin coat to the base of your tray and immediately sprinkle with glitter and shake around so it covers. If you have a large tray continue doing this in sections so the glue doesn't dry before you dust it with glitter.
Cover the entire base of the tray with glitter until you have a thick glittery base. You can always go over the glitter with more Mod Podge and sprinkle additional glitter if it looks spotty. Let dry for a couple hours until Mod Podge is clear.
Mix your clear epoxy or Resin as noted on the directions on the box. Pour contents carefully over the glittered base.