Client-side Fabric mods. I make Archetect: schematics as ghost blueprints, a printer that builds them for you, and an offline chunk cache that can rescue a build from a server you can no longer join.
A modern rebuild of the classic Schematica. Save any build and load it back as a translucent ghost you can build inside, by hand or with the Printer. Reads .schem, .litematic and .schematic, plus its own .archetect.