I sanded one mm off the surface before applying one layer of cf (200g). The carbon fiber gives 0.2mm thickness plus resin thickness. Epoxy resin is pretty flexible, so I think the stiffness/weight is very minimal.
This deck has semi-flex(not bamboo) Once it’s fully cured, I’ll find out the difference.
How do you lay the CF on the bottom of the deck?
I folded it over as you see the picture. It sticks like a glue; that’s what the base coat for.
So would you do 2 pieces of CF and sanwhich the board together?
Yes, I would, if you want the other side skinned as well, in my case, the grip tape will be on it.
The Easycomposites site has many good tutorial too on this topic and others. If you were to lay CF on the other side of the board as sais by Plumb77, there would be an overlap of the fabric on the edges. Does this disappear or his hidden when you do the various layers of resin, sanding and polish?
Yes, the edge can be sanded to be hidden, but it’s hard to apply resin to both sides at the same time. You might do one side at a time.
I meant as in, where did you order it from? Or did you make the deck yourself?
Would this method work if the carbon fiber was to be layered directly over foam core?
Ex: Layering from top to bottom of deck.
Carbon fiber Plywood Foam core (Sanded and shaped to create a housing for the electronics) Carbon fiber
Would recommend vacuum forming when doing it like that and possibly more than one layer of carbon over the foam.
I can’t believe you’re doing that directly on top of your Grandma’s rug! 
I have to give this a try… Any specific place to get the carbon fiber and epoxy? (Links would be extremely helpful, as this is all new)
Where did you get the kit from?
*Carbon Fiber Cloth Fabric 2x2 Twill 50"
Ha!
My Granny said it’s ok 
as long as she is getting a board.
Yes, the vacuum bagging is ideal for the project.
How much stiffness does this add? Or is it just for looks?
Also can I add two layers of cf using the same method?
From the videos I’ve found looks like it at some stiffness but mainly for astestics
Just for the looks. If you want to add two layers, I recommend vacuum bagging.