Worldbuilding

In the setting I'm working on, one of the ancient elven technologies they reverse-engineered is something they call "gossamer looms." Gossamer is the name given to the rose-colored threads of ethereal pseudo-matter that can be arranged in any shape imaginable to serve as the framework for fusing materials together. It's frequently combined with their illusory projection tech (magic mirrors) to do rapid construction with pre-existing templates. Feedstock (typically gravel, sand, sawdust etc) is drawn through a "loom" which can vary in size from handheld to so massive they require multiple levitation engines in order to be used at all. This feedstock shoots along the rose threads of light suspended in air to fuse to whatever template has been drawn in the air, either freehand or pre-recorded.

How exactly do the materials fuse together? Good question. The Mages' Guild is working on that one. But they have more pressing concerns, like the eternal maelstrom of lightning that they're barely containing following that storm bomb during the big war, or how to cleanse that peninsula where every dead thing that falls there rises up and sprints in the direction of the closest living thing to kill it.