How to save any item for builds?

I'm sure there's a video on this but the ones I found don't work. I'm in the process of collecting unique items across the map for a build and I know most of them you can fuse to a weapon or shield and deconstruct it later in tsrry town but some you can't. For example I am trying to save the u strut from the right leg depot, but you can't fuse it. The only way I know how is to fuse it to another item and save it in your favorite builds. I attached that sparkle fruit to it. But thr moment you knock it off or remove it, the strut disappears. Same thing if you attach a zonai device to it. Any help is appreciated.

On a similar note, some unique items found at the depot or shrines can be "broken " off like the fan blades at the depot. Yes there is a video, I can link it if you want. I think you use a rocket and that green zonai spike. Has anyone figured out how to get the large steam roller like wheel from the zanmik shrine?