To ensure a good protective function, I would advise using several layers of 200 g/sqm fabric, but you do not need to use expensive CF and Kevlar for all the layers.
I would use 2 layers of CF or CF/Twaron 200 g for the outside to provide impact resistance, and then diolene or glassfibre cloth for the middle 0 - 3 layers, then a final layer of CF 200 g twill
(if you want the cosmetic effect of real CF on the inside as well... This is not JUST about going lighter, it is probably also about going "cooler"
??
The number of middle layers can then determine the final thickness of the part.
If you think about it, your "helmet" will use up at least 60 - 70 cm of a 1 metre wide roll of fabric, and you will need at least 3 - 4 layers to provide a level of protection that will come close to that of the steel "helmet"
The method to use will depend on how accurately the CF/Kevlar protection dome will need to fit.
How is the protection dome/helmet held in place? (Secured for transporting the instrument)
The best result will definitely be obtained by using a little extra material and making a mold from the steel "helmet", then making the actual part from that-
You could buy some meters of glassfibre cloth (much cheaper than CF/Kevlar) and make a mold with that and normal EL2 laminating resin.
You would get a much better result, if you also bought the smallest package of clear epoxy Gel coat. That can be used for both making the first few layers of the mold, and for the protective CF "helmet" itself, giving a nice durable finish to it.
Process:
Very carefully wax and polish (5- 6 layers) the existing steel protective "helmet" add a flange from some suitable material. Be sure to not create a mechanical lock by filleting out with plasticine/was as needed.
Mix up some of the Gel coat, and brush this on the waxed and polished part and flange, in a nice even layer.. wait for it to reach "tack" state and repeat 2 more times.
When the last layer reaches "tack" mix up some EL2 and have the glass fibre ready cut into pieces that fit the shape/size of your mold.
carefully laminate the glass fibre up, building up maybe 5(?) layers, depending on how heavy the glass cloth is.
Leave the whole thing to cure for at least 24 hours... and carefully remove the original from the mold.
Depending on your demands for finish, clean up and polish the mold, and then wax it carefully, just like the original part.
Now you have a mold that will let you create more than one new "shell" from your chosen material.
Laminating the part will allow you to match the thickness of the original steel part, an should ensure a good fit on the actual instrument.
You can use precisely the same process as when making the mold... starting off with gelcoat, to get a strong polishable surface.
If you go very simple and laminate the "finished part" directly inside the existing "helmet" it will be smaller, and have the finish of the INSIDE of the steel "helmet"
Will it fit properly then??
Good luck with the project...
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