Cut a piece of bristol board or thin cardboard so it's slightly smaller than your canvas. Sketch out where you plan to place your LEDs and your Circuit Playground. Mark the spot where your capacitive touch button will thread through the canvas.
Measure out the appropriate length of neopixel strip. Find the "in" end of the pixels (look for the arrow on the strip, it may be partially obscured). Carefully cut through the copper pads between LEDs. Cut close to the "out" side of the last neopixel in your strand, leaving more copper pad on the "in" edge of the next pixel in line.
These 144/m lights can be difficult to solder. The pads are really tiny and very close together. We don't need to solder anything on to the "out" ends of the strips for this project, so we can sacrifice that part of the pad and leave more copper pad on the "in" side of the pixel, making the soldering a bit easier.
Lay out your strips on your bristol board, being sure the "in" ends are at the bottom. Secure the strips to the bristol board with clear packing tape, being sure the solder pads are accessible.
The 5v 2A power supply recommended for this project will supply just slightly too many volts for our neopixels -- they prefer around 3.5-4.5V for optimal performance. This is a nice, small, inexpensive power supply -- it's everything we want if we can just drop the voltage a smidge. An easy way to do this is to use a diode.
Diodes are meant to protect your circuit in the event of reverse polarity (like if you hook something up backwards). A side effect of adding this protection is that each diode you add will give about a 0.7V drop in your circuit. Perfect! That will bring our power supply to exactly the range we want.
Twist the legs of your diodes into little loops. Look for the silver stripe on the diode. The stripe should be on the side facing AWAY from your power supply. Solder a very short wire to the non-striped end and a longer wire to the striped end. Cover with heat shrink.
Place the short end of the red wire into the + pad on your screw terminal and screw it tight. Screw a long black wire into the - terminal. Tug on the wires to make sure they're really secure.
It's easiest to get the screw terminal to hold if you strip about 1/2" of shielding from the wire and then twist the bare wires into a little ball, which will fit snugly inside the terminal.
One of my favorite things about this stranded silicone wire is that it's easy to strip a little of the silicone shielding to expose a section of wire without cutting the wire. Just grab where you'd like to solder on a wire, then with a tight pinch and pull with your fingernails, expose a tiny bit of wire.
Cut several short red and black wires, long enough to reach your neopixel strips and your circuit playground. Splice the short wires to your long power wires coming from the screw terminal.
Tin the pads on your neopixel strips, checking again that you have the "in" ends of the strips down near the bottom.
Solder a red power wire to VBAT on your Circuit Playground and a black wire to G.
Solder the short power wires to the neopixel strips: red wires to + and black wires to - or G. Be sure you get the right pads -- the labeling can be hard to read on these tiny LEDs.
Solder a colored wire from pads 6, 9, and 12 to each "in" data pad on your neopixel strips.
Finally, add a longish colored wire to pin 10. This will go to your capacitive touch on/off switch.
Time for testing! Once all your connections are made, plug in the power supply and watch the flames flicker! Touch the bare end of the wire coming from your capacitive touch pad, and be sure the lights fade out and back on again.
Solder a short wire firmly to the back of your button. Twist the wire together with your capacitive touch button wire temporarily and test the button to be sure it works.
Some metal jewelry findings have a coating on them that will make capacitive touch tricky. If yours doesn't work at first, try soaking it in 99% alcohol for a few minutes. This will clean off any oil or residue and make the connection work better.
If your button doesn't work at this point, head over to the calibration page and try calibrating the code to the button.
If it still doesn't work, you may need to find a different thing to use as a button. Try copper tape or anything made from a clean, solid, conductive metal.
Once your button is working reliably, mount it on the front of your painting with the wire poking carefully through the canvas. Solder the wire to the capacitive touch wire coming from the Circuit Playground.
Attach the bristol to the back of your canvas with staples, leaving the power cord accessible. You can also cut a small hole in the bristol board so you can access the Circuit Playground's USB port, in case you want to change the code later on.