The parts arrive and I have five beautiful panels, art in their own right. But there is more to add to make them shine.

Ladyada said 1206 resistors are fine but it takes time, tweezers and a steady hand to attach them. Be sure you have a soldering iron with a fine tip. I did not use solder paste myself. If you are familiar with paste, you can order a stencil with the boards at an extra cost, place the parts and heat the board.

There are two types of tweezers in the Featured Products page for holding SMD parts while soldering.

If you have not soldered surface mount (SMD) parts with a soldering iron, see this tutorial.

For the ICs, I referred back to the schematic for orientation. As seen above, the left handed chip U2 has pin 1 facing the battery connector, U1 on the right pin 1 is pointing down to the components below.

I lightly tinned all the IC pads - not much solder at all. Then I carefully placed the chip in the correct orientation. Heating up a corner leg, it anchors the chip and you can review to see if the chip is still square on the pads. If not, heat and reposition. Once done, go to the opposite leg and tack that down. Then go one by one heating a leg to solder in place. If you are proficient at solder flux, you have an easier time of it.

Solder the battery holder with the + pointing down towards the bottom of the PCB.

Next solder the resistors. Be sure to get the 470 ohm on the right pads and then do the 10K resistors. Tin one pad, place the resistor on with tweezers, heat to affix then use light solder to get the other end affixed. Repeat for all resistors.

The holes for the LEDs to face into the board may be a bit small. I used a bead file, also called a needle file, to slightly enlarge the holes so the chunky center of the LED fit inside the hole. Drilling would be possible if the bit is only slightly bigger than the existing hole, be careful.

For the diodes, I found the small green vertical green line from the larger horizontal green line faced the top of the board (as shown, the small square faces to the battery holder). You can test yourself: put a battery in and then put an LED on the pads and touched the button to ensure it would light, then solder it (with the power off) correctly oriented.

Once all soldering is done, install a good battery and flip to the top side. Touch each number pad and the corresponding LED should light up.

Debugging

If one doesn't light:

1. Be sure the LED is positioned correctly. I found the small green vertical green line from the larger horizontal green line faced the top of the board.
2. Ensure the IC, resistors and LED for that button are making contact with the circuit board. Do not heat too much or a pad may lift off the board. 
3. If a whole row of LEDs doesn't light, double check the battery is good, the column IC is oriented correctly has power to the correct legs and all solder connections are good. A magnifying glass or illuminated microscope help here.