Light up your life! Opt in to this optic option with the most wonderful way to introduce kiddos (and adultos) to all of light's tricks. From refracting, diffracting, reflecting, diffusing, the light drum is just wonderful. This is one of our favorite projects for awesome science in the dark.

What: Light Drum!
Where: Your place!
Concepts: Optics, light, reflection, diffraction, refraction, diffusion
Time: ~ 2 hours to make one. If choose the cardboard box option, about 30 minutes
Cost: ~ $10 plus cost of bulb
Materials:
- Concrete form tube (12" diameter works well)
- Wood (small amount, we used 3/4" ply)
- Screws
- Brads
- Light Pendant (hanging socket)
- Bulb
- Black construction paper
- Stuff to make optics elements (lenses, mirror, color gels)
Tools:
- Saw
- Drill
- Clamps
- Utility knife
- Hot glue gun / hot glue
- Hole puncher (optional)

This was inspired by one of my favorite exhibits at the Exploratorium, and I wanted teachers everywhere to be able to create this concept at home. Let's illuminate!

Step 1: The Tube

Cut a section from your concrete form tube (anywhere from 9-12" is good). This is some hard stuff, but a good jigsaw will cut it like cardboard butter. Sand the top a wee bit at the end.

Step 2: The Drum Top

Trace the tube on some wood, and find the center of the circle. Cut the circle out so it fits snugly in to the top of your concrete tube. Our circle had a diameter of 11.5" (the internal diameter of the concrete tube).

Circle Nerd Alert: Finding the center of a circle is actually an amazing geometric process. My favorite way exists in instructable form here.

Step 3: Top Holes

You need a hole for your light, and also some vent holes to keep the whole system cool, and also make it look neat.

Measure your pendant width, and mark a circle in the middle for your light. For our's, the width was around 1.75", which we'll cut after the vent holes.

Choose how many vents you want, and using a protractor, space them out around your circle. For this one, I chose six, and spread them out so their centers are 3.5" from the center cutting with a 1" spade bit.

To cut the internal circle, drill a hole somewhere in the middle to start. Then jigsaw around until you get a circle-ish. It doesn't have to be perfect. Check at the end to make sure your light pendant fits in!

Step 4: Top It Off

Make sure it all fits, and then drill some screws in the sides to make sure the top stays! I threw in a couple screws by the pendant to make sure that stays snug, too.

Step 5: Filters

Oh so many fun ways to play with light! You can make tons of filters out of black construction paper, and trade them out at will. It pays to make them all the same size with corner holes in the same position to make changing them quick and easy. Cut them out however you want, and you'll probably find a hole-puncher is handy.

For ours, we made them 6" wide x 4" tall with pass-thru holes in the middle. It works great to have a mix, but we'd definitely recommend throwing in some colors, adding one with a single slit, multiple slits, and a few shapes for shadow experiments.

The files are attached here if you want to use ours as a guide!

Step 6: Attach Your Filters

Press on a sample filter, and mark where the drill holes are. Then, we can use a piece of paper to make a smaller window where light can pass through. We just eye-balled it, and outlined that on the tube as well.

Use a utility knife to make the window, and a drill for the holes at the four corners.

Step 7: Brad and Repeat!

You have your brads, you have your filters. Use four Brads to put the first filter on, and then make some more filter windows. For ours, we made three filter spots with 6.5" in between. A fun way to measure if you don't have a tape measure is to take a ruler and roll it along the tube to get an accurate distance measurement.

Finish it off by screwing in a lightbulb!

Step 8: Make Fun Optics Things!

Glue up your favorite optics things! We used some pieces of wood as bases, and then you add whatever you want. A few things we would recommend to get you started include:

Prisms -- great for dividing light. Either order online, or make your own out of clear plastic containers and water
Lenses -- grab these from magnifying glasses, sunglasses, cameras, or order online. It's great to get a mix of different concave / convex combos, and to play with different focal lengths.
Mirrors -- anything from craft mirror to mylar to cosmetic mirrors. Great to mix concave and convex here, too!
Other fun things -- A white background is good for seeing colors clearly. Black paper with a hole is good for seeing the shapes of shadows. Water bottles with colored water work great. Color gels are great for color mixing. Go crazy with it!

Step 9: Light It Up!

Turn off the lights, and learn about optics! There are many great challenges to do, and activities with a group. Some include:

What colors do you see with a prism with white light?
What about when you put it front of a color light?
What angle does light bounce off a mirror?
What do convex vs. concave mirrors due to light?
Can you re-make white light from different colors coming together?
What is the shape of light you see through a pinhole? Does it depend on the filter?

Most of all, enjoy seeing light in a new way!

Some tips on project modification include:

Get the brightest light that your socket can take. You want max lumens, baby! This will give better light rays coming out.
Cut your light drum short or lower your bulb down. You want as much light to come directly from the bulb, and not from reflections.
Narrower slits in your filters will make for sharper light rays.

YAY!