Of course I have been meaning to do this for a while (this and about fifty billion other things..).

So the picture is almost self-explanatory. The container lid is drilled with 4x4x2 holes (I bent the 1mm drill bit, so the first 2 holes are 1mm, the rest 1.5mm). The LEDs are inserted, all facing the same direction (oriented so the flat, negative side of each LED is on the same side!). The legs are then bent and soldered together horizontally, and then vertically. In between, I taped (masking tape!) over the previous soldered connections as a crude insulator.

Then I tested it with the multimeter (also a gift from my bro, but one that I got to build myself (with the soldering iron he gave me!)). Handily, the test current from the meter actually lights the LEDs up, which is great for "it's now lights out time, stop reading please" demonstrations to kids (at about 8.10 pm at our house).

Needless to say it works perfectly.

What next for my LED matrix?

Well, about a year ago I bought a whole lot of electronics components for my planned (predicted? hypothetical) USB-MIDI controller project. So the plan is to try driving the LEDs (simple strobed animations, etc) from an AVR brain through two 4051 multiplexers. I don't know much about how to do this but I will learn! Hopefully this will be then form a good light-up part for underneath a 4x4 button array in this supposed controller...