I am down for the 3D printed handle if it could be bolted to a metal blade.

It wouldn’t be hard to just remove the handle from a hardware store saw and replace it with this.

Might have to drill out the rivets, but that’s not too difficult usually.

I wouldn’t trust FDM-printed plastic to hold up structurally under actual tool use, though. It’s very likely to split and shear along the print lines.
Print orientation plays a big part in part durability. While an FDM print will never be as strong as an injection molded piece, I bet you could get it to 85% of the strength or so without any post processing.
This is true, but for something subject to as much focused, repetitive force as a working saw handle I’d still steer well clear.