Building curtains and matrices from fairy lights / seed pixels is a time consuming pain. The thin 24 or 26 gauge wires are very difficult to work with, doesn’t reliably connect with Wago connectors and sometimes JST connectors. And you will need to splice in numerous power injection points.
Notenoughlights, Tonyno and I have been working on a method to build custom LED curtains that don’t require sub-controllers above each strand. And we have come up with a method that is fairly inexpensive and most importantly is quick and easy to build. We have been working with a Chinese manufacturer Know Shine to develop a 4 wire seed pixel string. The fourth wire is connected with the data wire at the bottom of each strand and feeds the data back to the top where it is connected to the data line on the next strand. I tested the data return functionality and it works at least up to 15M. Know Shine can make the data return lights at 10cm, 5cm and 2.5cm pitch (10, 20 and 40 LEDs / meter).
To connect the lights, we use standard RJ9 4P4C connectors. Simply separate the wires with a razor blade, insert into the connector, and crimp it down. Cut the bottom of the strand 12mm / 0.5in from the last pixel, strip the ends of the data and data return wires, solder, cover with a small piece of 2mm heat shrink tube and hot glue a brass bead on the bottom to add weight. The whole process goes very quickly.
To make the spine, I developed two options; a 50cm long PCB for rigid spines and a 2CM PCB for a flexible spine. I will probably make a 50cm flexible PCB in the future. You can also get RJ9 female connectors with 4 wires already attached. Admittedly, the spine is kind of ugly, so it will need to be hidden in a mounting board.
Data return seed pixels 5cm pitch - $4.75 / 100 - $95 / 2000
RJ9 male connectors - $3 / 100
RJ9 - 4P4C female connectors - $10 / 50
7mm Brass Bead - $3 / 50
20x12mm PCB $8 / 50
Crimpers w/ 4P4C - $8
Wire stripper $8 (don’t try to strip 26AWG wire with your 22AWG stripper)