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This How to was provided care of
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Supplies needed
Carbon fiber cloth
Clear resin
Spray glue
sandpaper varying from 100-1000 grit

This technique is referred to as overlay. Usually used to cover interior pieces with CF. This can be used for exterior parts but the technique uses the stock piece and you mold the CF over the piece. The stock piece remains in place, so the finished piece is slightly larger than the stock piece. This involves considerably more hand work. The concept is covering the piece with carbon and resin. Then more resin to build up the thickness. Most of this resin is sanded off until a smooth surface is achieved. This is time consuming but the end result is worth the effort. After all, you’re doing this to make your car look great.

The part I’m going to demonstration is a B-pillar from a VW.
The technique-
If the piece is hard plastic you can sand the piece with 100 grit sandpaper. If there is a fabric covering you have two choices. The first is to remove the fabric and sand the basematerial with 100 grit paper. The second approach, although I don’t recommend it, is to cover the fabric with masking tape and then spray on three coats of clear Krylon. Allow the Krylon to dry and then scuff the surface with sandpaper.
The procedure is the same from this point on.
Before we go too far you will need to cut the material to fit around the piece. To help in how to make the cuts I’ve provided the following illustrations.

The technique-
If the piece is hard plastic you can sand the piece with 100 grit sandpaper. If there is a fabric covering you have two choices. The first is to remove the fabric and sand the base
material with 100 grit paper. The second approach, although I don’t recommend it, is to cover the fabric with masking tape and then spray on three coats of clear Krylon. Allow the Krylon to dry and then scuff the surface with sandpaper.
The procedure is the same from this point on.
Before we go too far you will need to cut the material to fit around the piece. To help in how to make the cuts I’ve provided the following illustrations.

Leave about 1/8” extra material to fold around the edges. This varies with the thickness of the piece. You will need to experiment here.

place the piece on the carbon and tape the edges.

Lay down a coat of resin mixed with hardener over the surface of the piece. Because the part is a light gray I tinted the resin so the gray would not show through the carbon. Tint is very cheap and a little goes a long way. It won’t bleed through the carbon fiber. Let the resin dry enough so that when you touch it with your finger it leaves an imprint but doesn’t come off on your finger.

Spray the back of the piece with 3M 77 adhesive and let it tack. Place the carbon over the piece. Fold the fiber over the edges and press into the adhesive, it should hold. For extra security, use masking tape to hold the edges in place. For the top coats on the carbon use clear resin. Use your brush to coat the edges of the part. Set it aside to dry. Don’t worry that things look messy at this point. This first coat is to adhere the carbon to the part and form a solid base for the remaining resin coats.

Once the part is tacky you can brush on the next coat of resin.
Allow each application of resin to tack before laying more on.
Continue brushing on more resin on the part until the fabric is covered and there is no sign of the twill weave showing through. This is important, you will be sanding these top coats of resin and don’t want to sand into the carbon. If you do the part will be ruined.

once the resin is solid and dry sand to level the resin. I know this looks horrible and you think you just ruined everything! Don’t worry just apply more resin to build up the low spots. Add a layer or two and sand again. Soon there will be a level surface.
Once the surface is level sand with 220, 400,600,1000 grit wet sandpaper.

Clean with soap and water then allow to dry. The surface will be dull. Now spray on several coats of clear Krylon. Urethane is superior! Isn’t amazing how instantly the twill appears and the depth. To achieve a deeper finish, spray on more Krylon.
Admire your work.

Overlays are simple to do but do take time. The resin needs to be completely dry before sanding. The steps are just as outlined. The most difficult part is wrapping the edges. You should practice the cut techniques I outlined. Try these with some inexpensive fabric so that mistakes won’t ruin the carbon fiber.
I’m working on the next installment. This will cover making a form (plug) and molding parts. It will cover multi-part molds and vacuum bagging. I really recommend you try the above techniques before moving to molds. Some familiarity with basic techniques will make the move easier with fewer failures.