Hey guys, just new to the forum however have recently been making a few different moulds (not yet pulled any parts but they all look good and nice and shinny). 

On a flat object like that and will very good release agents and good preparation you can do recesses if they are shallow.  Obviously you would fill the hole itself leaving just the countersunk recess.

A prime example is the recess on our subaru alternator cover:




And the shallower ones on our MR2 engine cover:



So it is possible to mould them and get a successful repeatable release.


The practicality of getting the carbon to stick exactly where you want it means it would be very hard to do those parts wetlay or resin infused, however pre-preg is dead easy as you can cut the fabric to any shape and it easily sticks where you want. Also lots of brute force can be used with blunt tools to force it into corners, the same kind of force that would shread normal fabrics.

If you wanted to do such things wetlay or infused then you would find it much easier with a ProFinish Carbon Fibre 2/2 TwillProFinish Carbon Fibre 2/2 Twill and some form of spray tack or applying when resin is tacky.  ProFinish can be neatly cut like pre-pregs and wont fall apart like normal fabrics do, so you can do some quite precise work with them.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant