Count out 24 hex nuts from the box of fasteners. The top and middle pieces each have 6 spots for horizontal nuts and 6 spots for vertical nuts.
If the "horizontal" nuts are a bit loose, you can put a small piece of masking tape over them so they don't fall out for now. Remove the tape when assembly is complete.
For the "vertical" nuts, it's important that they be well-centered with respect to the holes in the 3D prints. You can press them in by taking advantage of a hard surface like a table, and then use one an M2.5 screws to make sure that they are centered before continuing to the next step.
Next, solder the barrel jack onto the perma-proto board. You must place it exactly in the position shown, with the front pin in the top row, the rear pin in the 4th row, and the middle/side pin in the third row.
Bend the top pin down, the bottom pin up and the side pin right.
Using a small piece of wire, create a connection from the top pin to the topmost pad with the blue line to its right.
This will connect the power supply's positive side to the red (positive) rail and the negative side to the blue (GND) rail.
The Perma Proto is shown here on top of the bottom 3d printed piece, but at this point you should not screw them together. It's good to check the base part for correct fit, though, it could save you a tricky unsoldering operation later.
Instead, set the bottom piece aside and bolt the middle piece to the perma-proto in the orientation shown. You won't have enough screws to fill all 8 positions, but 2 or 3 provide an adequate mechanical connection.
Grab some of the middle length (M2.5x6mm) screws from the fastener pack.
Pick two LED strips of the correct orientation to go in the north and south positions and screw them in to the base piece and then into the top piece.
Take the red wire of the south piece and "thread" it through the bottom hole just to the right of the red line. Take the black wire and thread it through the bottom hole just to the left of the blue line.
Flip the board over, pull the wires completely through, and trim them to about ¾" length with side cutters.
Then, grip the bottom part of the black wire with pliers and use your fingernails to strip the insulation at least 1/4" from the end. Push the remaining insulation back through the hole, and solder the exposed wire to the pad. Repeat with the other (red) wire. Trim any excess wire with side cutters. At this point, it's good to test the LEDs by plugging in the power supply and turning it to 10V or more; the LED strip should light clearly along its entire length. Always unplug the power supply before soldering the next strip.
Repeat this process with the rest of the strips, working inward from the north and south ends to the center. When the remaining gap is too small for a hand, use the pliers to guide the ends of the wires into the holes. Be patient, always pay attention to polarity, and test frequently to ensure each strip works when it's added. If a strip doesn't light, the most likely cause is bad soldering; simply de-solder it and start again with fresh wires. In one case the author experienced, the pads at one end of a section didn't work but the pads at the opposite did. The LED strip may have been damaged by careless handling.
Once soldering is complete, the remaining step is to bolt the bottom 3D printed piece to the perma-proto. Like the middle piece, there won't be enough screws to bolt all the positions, but 2 or 3 positions are enough to give adequate mechanical strength.
Use the variable power supply to adjust the brightness, and add an in-line switch if you want to turn the lamp on or off with a decisive click.
Want to hone your own 3D design skills? The author ran out of time to design a snap-in cap piece that would hide the wires. Maybe you'd like to try your hand at it. A version that is designed for hanging from the ceiling would also be excellent.