Building a Speargun a little differently

So I had this stupid idea of building my own Speargun. I get bad ideas regularly, but I just had to develop this one a little further.
I've worked in manufacturing for a long time, from machining metals and plastics to composites and now additive manufacturing (3D printing).
Why not put all of them together?
The main structural element is based on an aluminum channel that will form the "spine" of the gun. I then printed the "shape" on my 3D printer.
All of this will be covered in fiberglass at first for the prototype stage. The bottom will receive some unidirectional carbon to add stiffness in the vertical axis. The track for the shaft will be poured and then machined most likely on a router table.


Let me know what you think or if you have any concerns before I move on.