All this time and waiting and the thing that makes him remarkable is "he lived in a modern era so he knows stuff" ? Really.... that's.... any of us could replace him. A magazine could replace him. Google images could be the mc atm.
I know this is an isekai fish out of water trope, but to distill it down to this point... isn't it trying too hard to emphasize the mc is a regular, normal person with no significant qualities (yet) ?
There's nothing specific to like about the mc, still. Oh,but he's a walking 3D printer... that Supposedly can't make malevolent things? What? What defines that in this case? If a sword is fine, is a nuke?