Hi
I made a carbon front fender for my Husqvarna 701 Supermoto in a four part mould. The part of the mold that depicts the assembly area is cast from polyurethane.
 
I fill the mounting area of the front fender with a thickened resin before vacuuming.
I use about ¾ teaspoon chopped carbon fibre strands on 65 g of resin.

The result looks neat, but the assembly area is more brittle than I expected.
It sometimes breaks when I drill it. I am afraid it will break in rough use.
If possible, I do not want to build a new mould.
Any suggestions?
Regards
Frank