[@Dark Cloud] The way I imagined it working would is that the Core basically deploys a network of needle-thin crystalline veins (that have prehensile motion) into nonliving materials that it deems usable in order to "attach" them.

It wont use gravel or particulates, or anything like that. It has to be CHUNKY (figuratively ofc).

The only thing it CANT use its repair skill on is the core itself-- which essentially functions as its brain and heart combined. 

Its not repair like welding-- its more like swapping pieces in and out as they break or wear down. Does that make sense?