I built a cat like that some years back. It lives in my back yard in bits, the windsurfer mast substituting for a an early spinnaker pole for my F14.

I used 50mm (2") dia scaffolding tube for my tramp frame and hiking rails and employed the end fittings to connect it all together. I put surfboard fin boxes in the decks and bolted fabricated channel brackets to those to support the tramp frame.
I intended to have the hulls articulate to accommodate the angle of heel. Steering came from the mast raking back against a big bungy as the sheet was tightened [no rudders].

The articulation concept was flawed but it sailed well in light breezes.

I probably should have continued with it's development but something else distracted me at the time.
As best I can remember there are no pics.