Make an Acrylic Rainbow Light

Let's make an Acrylic Rainbow light! It's fun, fabulous, and features multiple operating modes that can be customized through Arudino. This project uses WS2812 individually addressable LED strips and an Adafruit Trinket to light up the acrylic arcs. Simple design yet very effective; a beautiful art piece to light up any room!

Supplies

Tools:

• Access to a laser cutter/engraver.
• Soldering iron (and some basic skills).
• Wire stripper/flush cutter.
• Dremel (to clean up some edges).
• Small screwdriver / pliers.

Components:

• Cast clear 3/16" Acrylic sheet, at least 24" x 12". Prefer P95 matte on one side.
• Black opaque 3/16" Acrylic sheet, at least 24" x 12".
• 1ft WS2812 RGB LED Strip, 144 pixels / meter. Non-waterproof type. Adhesive back.
• 1x Adafruit Trinket 5V.
• 4x small 3/8" Rubber Feet.
• Small piece VHB double sided mounting tape.
• 12x M2 x 8mm screws, prefer black with button head.
• 4x M2 x 10mm screws, prefer black with button head.
• 4x M2 washers.
• 6x M2 x 10mm F-F standoffs.
• 1x 5.5mm x 2.1mm DC Jack.
• 1x tiny toggle switch, SPST.
• 1x tiny toggle switch, SPDT.
• 2x 100 ohm through hole resistors, prefer 1% tolerance.
• 1x 10k resistor, for pull-up (can vary).
• 22 - 26awg hook up wire, prefer solid core for cleaner routing.
• Acrylic adhesive, prefer Weld-On #4 (get one with applicator bottle).
• 5V AC Adapter w/ 5.5 x 2.1mm plug, at least 1A. Center positive.

Step 1: Gather Materials

First step is to gather all the materials! Make sure you order the right acrylic type and sizes. We're working with 3/16" acrylic and it should be 'cast' type to ensure we can engrave it.

I experimented with different types of clear acrylic and the best I found for light transmission is the 'P95' type linked above to Home Depot for purchasing. I use the Matte side of the acrylic for the front of the arcs and the backside is completely laser engraved. This allows light to bounce off the back of the acrylic and be visible from the smooth matte front.

Note: The image above uses completely clear acrylic which was used for the first revision :)

Step 2: Laser Cut Acrylic

Quite possibly the most important step! Get over to your maker shop, work lab, or friends garage that has a laser cutter capable of cutting a panel at least 24" x 12". Cut the black opaque acrylic first. Make sure to leave the protective film on to avoid scratches. Secondly you'll etch and cut the rainbow arcs, see below for details!

Included below is the FreeCAD 3D model which contains the entire Acrylic Rainbow model. I have also already exported just the black sections in *.svg vector format which is ready for laser cutting. The black lines should be vector cuts all the way through, the

Black Opaque Base:

Leave both sides of protective film on. Vector cuts all the way through, indicated by the black lines on the CombinedBlackAcrylic_Rev1.svg file. The blue lines should be rasterized etches which are used as reference guides which will help align the LED strips later. The dimensions are already adjusted for about a 0.2mm kerf (thickness of the laser cut).

Clear Rainbow Arcs:

Remove the protective film on the completely clear shiny side (if you're using P95 acrylic). If you're using regular clear acrylic then remove the film on both sides.

Use the ArcFullEtch.svg file to completely etch the first side of the acrylic (non-matte side for P95). Take note of where the etch is in relation to the acrylic panel so we can align the vector cuts later. I used a 120W CO2 laser with 10% power and 100% speed, Stucki dither (to smooth out the etch). You can play around beforehand with different smoothing techniques like placing the laser out of focus by 1/8 - 1/4".

After the full etch, flip the acrylic panel and use the RainbowArcsAcrylic_Rev2.svg to completely cut out the arcs (black lines). Ensure that the cuts will line up with the previously etched area (on the opposite side). Afterwards, do the small blue rasterized lines (these are guides for aligning the arcs later).

Source files (CAD, vector files, firmware) on Google Drive.

Note: Blue lines indicate raster, black lines are vector cuts all the way through

Step 3: Glue Acrylic Base

Remove any remaining protective film from the black opaque acrylic. Build the black base up and use painters tape (or any tape) to hold together the pieces in place. Make sure things line up properly and flush before you glue anything down. I like to use the tape to tighten up the edges so that things will glue down nicely.

Only the bottom 5 black base pieces are glued (bottom and sides). Leave the top piece (with square arc openings) alone for now.

Use the Acrylic Adhesive and the dispenser bottle to lay down a bead of glue along the mating edges of the acrylic pieces. The Weld-On #4 will seep into the cracks nicely. Wipe off any excess glue quickly or it will leave a mark on the acrylic.

Allow the base to sit undisturbed for about 1 hr so it has time to cure. Afterwards remove the tape and clean off any residue with some isopropyl alcohol.

Step 4: Add Rubber Feet

Use four M2 washers, four 10mm M2 screws, and four 10mm M2 standoffs to secure the rubber feet on the 4 corners of the base.

don't overtighten the screws otherwise the rubber feet will start to deform too much.

Step 5: Start Soldering!

Cut, strip, and tin some solid core wire and solder it to the barrel plug jack and toggle switches as show in the picture. Give yourself enough length to make the connections on the base easily. I left off one pin of the SPST switch disconnected because it will mate with the barrel plug wire.

Step 6: Attach Switches and Jack

Pass the switch and jack wires through the back of the base on the corresponding holes, see the picture. The SPST switch should be next to the barrel jack, the SPDT mode switch is the left-most one. Use the switch and barrel jack nuts to secure them to the black acrylic base.

Step 7: Dremel As Necessary :)

The barrel jack nut is slightly taller than 10mm, which means it's hard to turn it and secure the barrel jack unfortunately. Nothing that a little Dremel cut off wheel action can't fix ;). I sanded down an indentation at the bottom (inside the black base) and the bottom side of the lid of the base as shown in the picture.

Step 8: Add the LED's

Cut the LED strip down to 20x LED's on each side (about 1/2 foot). Make sure to cut along the mark exactly between LED's. A flush cutter is nice for this purpose. Straighten out the LED strip before we peel the adhesive backing.

Use the laser engraved guides on the bottom of the base to align the LED strip. The dividing line between LED's should line up with the laser engraved marks as shown in the picture.

Step 9: Secure the Trinket

Cut a piece of double sided adhesive about 20 x 15mm and secure the Arduino Trinket to the bottom of the base. Align the USB port to the opening at the back of the base.

Step 10: Solder Connections

Solder up all the electrical connections. Cut and strip 24awg wire to make the connections. Here is the order and wiring instructions. See the attached wiring diagram for reference.

Power

• Barrel jack positive (center pin) to the SPST switch first pin.
• Barrel jack minus (outside pin) to the Trinket GND pin.
• Barrel jack minus (outside pin) to the GND connection on the LED strips (two wires).
• SPST switch second pin to 5V pin on Trinket.
• 5V to the PWR pin on the LED strips (two wires).

Switch

• 10k ohm resistor between 5V pin on Trinket and Pin#2.
• Center pin of the SPDT switch should be wired to GND.
• One side of SPDT switch to Trinket Pin#2 (where 10k is).
• Other side of SPDT switch to Trinket Pin#3.

Data

• Twist 2x 100 ohm resistors together and solder them to Trinket Pin#0. This will essentially be duplicating the digital LED signal to both LED strip portions.
• Solder each 100ohm resistor to each of the data pins on the LED strips.

See wiring diagram for connectivity reference.

Step 11: Attach Remaining Standoffs

Use four M2 x 8mm screws to secure the remaining four 10mm standoffs in the center of the base.

Step 12: Power-On Test

Use the 5V AC adapter to perform the first power-on test (smoke test). The green LED on the Trinket should light up.

Step 13: Flash Firmware

Use a Micro USB cable to connect the trinket to your PC. Open up Arduino IDE and load the firmware onto the Trinket. Instructions can be found on the Adafruit website: https://learn.adafruit.com/introducing-trinket/programming-with-arduino-ide

Make sure the 'mode' select switch is in the middle position. The switch shares a pin with the USB port so it won't work if you have the switch toggled (USB signal will be shorted). The LED strips should light up when the firmware is loaded!

Attached is the source code. See the documentation in the code for additional information on the configuration of pins, etc.

Step 14: Secure Base Top

Remove the protective film from the top of the acrylic base. Use 6x M2 x 8mm screws to secure the base lid.

Step 15: Insert Rainbow Arcs

Remove any remaining protective film from the acrylic arcs. Use isopropyl to clean off any etching reside from the arcs.

If the fit is too tight, you may need to use the dremel to lightly sand the edges so that the arcs fit in nicely. The tolerances are such with cast acrylic that this may be the case.

Insert the arcs into the black base through the square holes on the lid.

At this stage you may also choose to apply acrylic glue to the arcs where they meet the base.

Step 16: Enjoy!

Turn off the lights and enjoy the beautiful rainbow acrylic art you created! The 'mode' toggle switch allows you to cycle through different operating modes which fade in/out different colors and perform a chase action.