This is how I did it, not necessarily the simplest/best but here it is:

Disclaimer: All protective equipment and normal shop practices should be followed. I take no responsibility for any damage/accident caused whislt following this write up

First off, wrap your seat in clingfilm to stop it getting damaged and to make removing the mould easier. (Personally I bought a second seat to play with)
Cut card formers to make vertical sides around your pillion seat area to contain spray foam and fix in place with tape. Apply spray foam inside formed area and allow to expand and dry:

Once the foam has dried out, take a large carving knife and cut to the required shape:

Wrap your newly sculpted foam mould and seat in clingfilm. Draw your cowl shape on the clingfilm with permanent marker to give you something to work to.

Cut out your 450 weight fibreglass mat to the rough shape of the finished cowl, this makes it easier to work with.

I used 450 weight fibreglass matting and fibreglass resin to make the cowl, details of how to mix the resin and catalyst (hardener) can be found here : http://stores.ebay.co.uk/The-fibregl...ating-GRP.html
I decided to use a velcro strap to hold the cowl to the seat once finished, so I cut a 4" wide strip of 450 weight fibreglass matt and soaked it in fibreglass resin first before laying it over the mould. The velcro strap was then applied over that and more fibreglass resin applied. Now apply resin to the areas within your pre-marked cowl area (I used a cheap 'throw away' paintbrush) and lay your pre-cut matting over. Brush more resin on top to soak the matting which will become more pliable the wetter it gets. Use the brush to form the fibreglass mat to shape and to push out any air bubbles.


Try to form the fibreglass under the seat to conform to the contours once on the bike. You can see the ragged ends hanging down under the seat in this picture:

Apply a 2nd sheet of fibreglass mat over the still wet mould, soak with resin and form in the same way as the first layer.

TIME FOR BEER You now have to wait for the fibreglass to harden, which could take anything from an hour to overnight, depending how thrifty/heavy handed you were with the catalyst

With the fibreglass all dried it's now time for some Dremmel work If you used permanent marker to draw on your cowl shape before you started fibreglassing, the lines will have transferred through the fibreglass and you will be able to see them. Carefully cut off the excess material under the seat first so that you can remove your cowl from the seat.

Cowl and seat now seperated, start cutting the excess off around the front part to form your basic finished shape. I forgot to take any pictures but be sure to test fit the seat and cowl on the bike at this time so that the cowl a) fits on the seat once on the bike and b) the bottom lines of the cowl folow the lines of the bike.

With the basic shape now all cut out you can now proceed to topcoating your cowl, this will give it a decent surface to sand to shape without compromising the strycture underneath. Make sure you use flowcoat/topcoat and NOT gelcoat. Gelcoat WILL NOT dry in the air and should only be used with a negative mould where the gelcoat will be covered with fibreglass. You can add liquid wax to gelcoat (up to 4%) to turn it into flowcoat if you bought the wrong stuff/have gelcoat already.

Once dry, again this depends on how much catalyst you aded to the flowcoat, take your electric sander and sand the surface down to roughly the required profile. If you have some deep dents in the surface, due to a poor foam former (like I did ), use a fibreglass filler such as Isopon IP40. This comes with a pink catalyst so is easy to see when completely mixed and is also easily spotted on a white flowcoat surface. Fibreglass filler is different from body filler (aka bondo) in that you can actually see the fibreglass strands suspended in the resin in the tin and will readily stick to fibreglass panels.

Once sanded down, I used 80grit for speed/ease of use, mix up some body filler (bondo) to fill the smaller imperfections and once dry sand with 120, then 240 to a smooth surface.

Now that's done and washed off, allow to dry and spray with filler primer. This can be wet sanded with progressively finer wet and dry to achieve a nice smooth finish ready for primer/basecoat/topcoat.

I'm not going to go into the whole painting thing here as it has been done before on this site, ig you missed it check out http://katriders.com/vb/showthread.p...nting+plastics