Question for those who have crafted baffling seals, how did you go about crating the shape and fit of them ?

Maybe take a look at some others to start. Then you can see what you want to do different. Usually acrosss the back of the engine is the most challenging. Wherever the aluminum engine baffling takes a "side step", I usually either make a perpendicular slit or begin a new section and slightly overlap the previous section.
Also by replacing the top cowl, and looking in with a flash light, you'll see where you might have to make a perpendicular slit just to get rid of a "lump". Cut each section a couple inches longer than you think!! That way you have enough material to overlap and fasten to the next section. Then trim it later. My mistakes are usually made by being too frugal and cutting the pieces too short AND not ordering enough material because I'm too cheap.
The orange silicone stuff works well for me. Buy extra, you'll need it. Cut it and put it in place using clecos first if you can get your hands on some. A pair of hole punch pliers used for leather, work well for making the holes. Spruce sells aluminum wide area baffle pull type rivets as well as the aluminum screw and nut fastners. I use both.
Hope this helps.

All intel is helpful and good On the Fly, thank you

If your baffle has a curved section, such as on the top rear following the curve of the cowling, you can get the seal to “cup” forward a little by stretching the outer edge as you rivet it , or allowing small ripples in the inner (riveted) edge. This cupping will give the seal natural memory so you don’t have to fight it to bend the correct (forward) direction every time you cowl the plane. If you do it too much though, the seal will not press against the cowling and won’t get a good pressure seal. Just want it slightly cupped forward so it biases that way.