Drill or melt a 1/4" hole into the center of the dome. If you're drilling, start with a smaller drill bit and work your way up through 2-3 sizes to minimize the risk of breaking the acrylic. If you're melting, use a soldering iron with a tip you don't care about and push it right through the plastic. Make sure your window is open so you don't breathe the fumes.
We'll use glue dots to stick all the pieces together. These things are great. They're not messy, and they have a really strong hold after just a few minutes.
If you mess up and need to get them off, 99% alcohol will help release the stick.
Open up your Circuit Playground case. Find the case bottom (the one with the screw hole in the middle). Stick 3-4 glue dots on the outside of the case around the perimeter.
Cut pieces of colored cellophane wrap to around 12" square. I like the look of rougher edges rather than tidy corners here, but don't worry about the shape too much. You'll have time to finesse it later.
Put a few glue dots in the center of your first piece of cellophane.
Wrap the cellophane layer around your ball, sticking the glue dots to the plastic firmly.
Put the top on your ball, then wrap the cellophane around the whole ball and secure it loosely with a rubber band.
Gently heat the cellophane with a heat gun or hair dryer. It will shrink to fit the ball. Don't heat it too much or you may melt holes in it.
Repeat with your second layer of cellophane. I like to put the lighter / more transparent layer on the outside since it give such a lovely depth of color.
Gently melt the tops and corners of the cellophane layers. You can trim off any too-long bits with scissors. It's also fun to cut little flaps in the top and then melt the edges a bit, to give a nice random flame look.
Gently open the top of the cellophane and pull out the top half of the ball. Put a glue dot on your battery, and plug the battery into the Circuit Playground. Place the Circuit Playground inside the bottom of the case, and slip the case top in to click it in place.
Stick the battery someplace out of the way, along the edge of the ball.
If you like, add a little more crumpled cellophane over the Circuit Playground to further diffuse the light for those looking down on the fireball.
Melt a small hole in the cellophane aligned with the screw hole in the bottom of the fireball. Melting works better than cutting here. If you cut the cellophane it's likely to tear, but a melted hole will stay put.
Slip your fingers through the rings so the fireball hovers above your hand. Shake it around to be sure everything is secure, and watch the lights flare up!
Reach in and press either of the Circuit Playground buttons to turn the lights off.
Turning the lights off with the buttons will lengthen your battery life, but the buttons do NOT cut power to the Circuit Playground. To turn the fireball fully off, you'll need to unplug the battery. If you just leave the lights in the "off" mode, your battery will slowly drain -- no bueno!
It might not hurt to get a couple extra batteries, and always have your charger on hand.