I want the table to look pretty while the lights are off as well as on. The electronics are mounted below the table top, so I need a design which gracefully hides the electronics while letting as much light through the table as possible.
I used 2x2 pine boards for the weight-bearing legs, staining them a nice matching walnut color.
I used a laser cutter to cut 8 decorative legs from birch plywood. I stained these to match the pine board legs and then glued them together using wood glue.
I added angle brackets to the weight-bearing pine legs and then screwed the legs onto the table, being sure to carefully line up the laser cut trees so they were perfectly flush with the edge of the table.
Next I trimmed the four "skirt" edge pieces down to fit, then glued them in place on the inside of the laser-cut trees, flush with the underside of the table. I clamped them in place until the glue dried.
I want my LED lights to shine through with beautiful diffusion, but also to allow some ambient light to shine through the resin when the lights are turned off. To achieve this, I suspended a plexiglass platform an inch or so below the table, with the light strips glued to it, facing inwards.
I cut the plexiglass so it runs the full length of the underside of the table, fitting neatly between the skirt pieces. It's not as wide as the table, but that works out fine -- it just needs to be big enough to fully cover the river section, not the whole table.
I placed my plexiglass on top of my table and sketched out where I wanted the lights to go with a sharpie. Then I sprayed two coats of Mirror Effect spray paint by Rustoleum into the area between the lines. This creates a one-way mirror effect -- the mirror spray reflects the lights upward to diffuse them really well, without blocking all the light coming up from below.
Next I glued the LED strips to the plexiglass along the lines. I made them about an inch wider than the actual resin river so you can't easily see the individual LEDs from above.
The silicone strips encasing the LEDs make this a bit tricky. Hardly anything sticks to silicone! The best thing I've found for this is Devcon Silicone Adhesive. This stuff is magic -- nice and thick and goopy, and seems purpose-made for sticking NeoPixels to just about anything.
I used 2" wood screws to secure the acrylic sheet to the bottom of my table. I carefully drilled four holes in the acrylic, outside the "river" area. Acrylic cracks really easily! Then I screwed the sheet to the underside of the table, leaving about an inch gap between the table and the acrylic with the LEDs positioned right below the resin river.
The objective here is to have enough space between the plexiglass and the table for diffusion, but still hide the whole electronics assembly inside the "skirt" I made out of the table sides.
I threaded the Circuit Playground Express around to the underside of the acrylic and stuck it on with a square of sticky-back velcro. I added some heat shrink filled with hot glue to the screw terminal to keep the wires firmly in place, then used staples to secure it to the wood of the table. I ran the power cord down along the inside of the table leg to the floor and attached it with staples as well.
Once all the glue dried, I turned the table upright and plugged it in. Suddenly all the imperfections, bubbles, streaks, and wobbles ceased to matter. This thing is stunning. I want to write a novel at it. I want to serve exquisite fine food and wine to interesting people while engaging in witty conversation. If I could invite three Notable Personages from History to a dinner party, I'd seat them at this table. It's a table worthy of a fairy queen or a Narnian King.