Matrix Model Builder

It writes a custom model: a grid of pixels with the node order set by how you wired them. That is the file xLights wants when a prop is not one of its built-in shapes.

It does not know your controller, your start channel or your universe. Set those in xLights after importing — they belong to the controller, not the model.

Max nodes per string only warns you here. Where a display physically splits across outputs depends on your controller and your power injection, so the number is a check, not something baked into the file.

Import with Layout → Import Custom Model, or drop the file into your xLights show folder.