Step 1: Gather Materials
- two 40" x 40"panels of clear acrylic 1/8" sheet
- one 40" x 40" panel of black acrylic 1/8" sheet
- one 37" x 7" panel of orange acrylic 1/8" sheet
- many feet (over 100') of colored acrylic rod (fluorescent colors work best)
- three fluorescent light fixtures and bulbs
- two 110 volt ac cooling fans (McMaster-Carr 1976K14)
- several square feet of 1/16" santoprene rubber (McMaster-Carr 86215K22)
- a good quality rubber cement designed for one-sided application. If you can get your hands on some Devcon Industrial Rubber Adhesive 14900, go fir it, it seems to work a bit better then other types.
- assorted nuts, bolts, and wood screws
- one 4' x 8' sheet of 3/4" sanded plywood
- scrap 1" x 1" for supports
All of the acrylic was purchased from Tap Plastics.
The rest of the pieces can be purchased at Home Depot or your local hardware store.
Step 2: Cut Your Acrylic
The Giant Lite Brite has three total layers of acrylic inside. The first and second layers have holes cut in them and are spaced 1 inch apart from each other. The third layer of acrylic is just a solid sheet which acts a backer board to stop the pegs from pushed in too far.
The first layer of acrylic is black, and guides the peg into place. The second layer is clear, so that light can pass through it, and is an exact copy of the front layer, just set back a bit so that it can lock the back of the peg into place on each and every hole.
That means you've got to find some way to cut all those uniform holes in two sheets of acrylic so that they line up perfectly. Stack the sheets if you can, and gain access to a CNC router, large bed laser cutter, or waterjet if possible. The holes could be drilled by hand, but be prepared to drill for a while.
I cut the acrylic on the Squid Labs' waterjet. I drew a circle that was just slightly larger then my 1/2" acrylic rod in the waterjet software, set a cut quality of 2 (below normal so it would go faster) and then used the Copy & Nest function of the software to lay out a grid of 37 x 30 circles. While I was at it, I loaded a .dxf version of the Instructables logo into the software to put at the top of the Lite Brite.
Leave the paper on the black sheet acrylic so the shiny top side doesn't get all scratched up with garnet as the waterjet cuts. You can take the protective paper on the other layers though, their surfaces don't matter as much since they are hidden inside the case.
Set the waterjet to start cuts using a low pressure pierce and tell the cut software that it's a brittle material. If you don't the acrylic will blow out and you won't have clean edges or a correctly cut part. Then, set up a movie, do some jumping jacks, or call your mother since the job runs for about 3.5 hours and should be ideally be babysat the whole time.
Step 3: Build a Frame
The first is a 1/8" groove close to the front of the frame that will hold the face sheet of acrylic in place. The second is a 1/4" wide grove set an inch back from the first grove that will hold the two clear pieces of acrylic sheet sandwiched together. The third and final groove is significantly wider - 3/4" and holds the backer board of the frame in place. Pass the ripped down sheets of plywood through the table saw with the blade height set to about 3/8", half the thickness of the plywood.
The exact distances between the grooves here really don't matter. Just give yourself about half the length of your peg between the front sheet of acrylic and the clear second sheet so that the peg is securely held in place - two inches of peg means a one inch gap between grooves.
Then, give yourself enough room to comfortably fit in your light fixtures and fans between the second sheet of clear acrylic and the backer board. The Lite Brite I built is 9" deep, has the front face sheet of acrylic set back about a half inch from the front, the second and third sheets set back an inch from there, about 7 inches of empty space behind that for the lights and fans.
The back board was cut to be the same size as the acrylic sheets - 40" x 40", from a laminated fiber board. It holds the whole Lite Brite together and has the lights, fans and supports mounted to it in the next step.
Once the backer board has been cut and the plywood has all been cut with the necessary grooves, you can cut the plywood down to length using a miter saw set at 45 degrees so that when you assemble the frame - you don't have any exposed edges. Cut the plywood into panels that will fit around the backboard and the sheets of acrylic while leaving as little wiggle room as possible.
Step 4: Install Fans and Wire Up the Lights
The bulbs are in a closed space and as such, tend to get pretty hot when you have them turned on for several hours. The ballast is probably heating up more than the bulbs themselves, but in any case, all that heat could cause problems over long term use.
To help dissipate heat, I drilled five 1.5" holes in the top panel of the case. Inside the case I mounted two 3.75 inch rotary "case" fans from McMaster that run off of the same 110 volt AC plug. Heat buildup was a real problem until I installed the fans. Once they were in, the case ran as cool as a kitten.
Along with the lights and fans inside the case I had to install some wooden supports which hold the back of acrylic stiff and in place. Aside from the supports, the acrylic sheets are only held in place along the edge of the case, so some kind of bracing system was necessary. I used some simple 1"x1" scrap cut to length for supports and screwed them into the acrylic sheets and the backer board with wood screws. Careful pre-drilling those holes in the acrylic - it cracks easily.
Step 5: Laser Cut the Santoprene and Glue It On
I ordered 6 12"x24" sheets of 1/16" Santoprene (a type of rubber that plays nice with laser cutters) and made up a pattern of slits in Corel Draw that matched spacing of the holes in the acrylic and that could be tiled easily so that I could use multiple sheets of my 2 sq. foot rubber to cover the entire area of the Lite Brite.
Once the file was done, I laser cut each of the 6 sheets with the pattern and glued the sheets behind the front layer of black acrylic using the special cancer causing industrial adhesive - Devcon Rubber Adhesive 14900.
I crudely rolled the adhesive onto the back of the front black acrylic sheet, so as not to get it on the parts of santoprene that would ultimately show through the holes, allowed it to dry until it was tacky, and then put the santoprene into place and applied pressure until it set.
I found that putting a small section of an adhesive roller onto my own applicator - in this case a cardboard tube - was more effective then rolling it on using a conventional paint roller.
Step 6: Assemble the Giant Lite Brite
Start by fitting the four panels around the back board. The backer board should slide right into the groove which you cut for it using the table saw. If it doesn't widen the groove by passing it through the table saw again, or spray some silicone into the groove to help it slide along.
Then, stack the two clear acrylic sheets on top of each other, putting the one with the holes on top, and slide them together into the middle 1/4" grove that you cut out for them in the plywood.
Before the final front panel could be slid into place I realized that I would need another set of supports to bridge the 1" gap between the two clear acrylic sheets and the black front sheet. 1" bolts weren't the most obvious choice, but they turned out to work really well.
I drilled through the two layers of clear acrylic, slid the bolt through from the back, held it in place with a nut, and repeated the process a few times spaced periodically throughout the entire sheet. The front sheet would rest on the bolts secured to the second set of acrylic sheets, which in turn would rest on the wooden supports that were affixed to the backer boards.
Before we sealed up the last side of the case, I turned everything on and made sure that everything worked properly. After giving it the final check, I slid the last panel into place on the side and used plenty of wood screws at each corner to hold the whole thing together.
The Lite Brite was outfitted with eye hooks so that we could secure it easily to a table or sawhorses when we bring it events like Yuri's Night and The Maker Faire. This step is completely optional of course.
Step 7: Cut and Pollish Acrylic Rods
Yellow, fluorescent green and fluorescent red worked really well at transmitting the light through the rod - so I'd definitely recommend some testing with specific colors of whatever rod you get to see what works for your application.
I did some experimentation using clear rods and spray painting them with translucent paints (Krylon brand and Tamiya clear model spray paint). Some of the tests turned out pretty well, but in the end only the blue painted rods were good enough to use in the final version.
Step 8: Field Test the Lite Brite
Before the Maker Faire, Mitch and I added on some small nuts, bolts and wide washers to mechanically hold the rubber in place. This was done before the event right outside the exhibit hall in a moment of haste and didn't really do much to help the rubber stay in place since it was so elastic. I can't recommend this as a solid method for holding the rubber in place, but at the time, it was all we could do.
Although the Lite Brite provided hours of fun entertainment for people attending the fair, its rubber backing suffered quite a bit from all the use and came completely off in many spots.
Plans are in the works to waterjet a permanent solution: a steel sheet bolted directly behind the santoprene that holds all the sheets of rubber in place. The sheet will be thin gauge steel that is cut using the same file that the front panel of acrylic was cut with. Except for one change - the steel rubber backing plate will have just a slightly larger hole diameter then the black acrylic to allow for the santoprene tabs to fold back easily when a peg is pushed through.
Updates to this Instructable will follow once the sheet is fabricated.
Step 9: Lite Brite, Lite Brite, Turn on the Magical Colored Lights
***This project is in no way intended to have anything to do with the Hasboro Corporation's Lite Brite product, licensing, or copyrights, and any resemblance to such product, licensing or copyrights is purely coincidental, subjective and likely false.***