I recently did some modifications to my rear bumper to make it look like a JDM one. Getting hold of a JDM bumper proved difficult and potentially expensive so I thought; how hard can it be to make one. I despise the look of the EURO one with its ridiculous black plastic shit shroud, and I'd seen form other threads that beneath all that laid a cut up JDM bumper.
The job was done with use of fibre glass. I didn't have any bodywork experience really, only worked with composites in the past. You really don't need any skills to do this; just some patience.
Tools and stuff:
Tools for removal of all necessary parts.
Glass fibre weave and matt
Polyester resin
Cardboard ply
Release wax
Bodyfiller
Sandpaper and primer
After removing the plastic crap, low and behold there was a roughly cut JDM bumper. It looked like the literally cut them by hand and didn't retool anything as the cuts were wavy and asymmetric. Luckily some of the number plate compartment had been retained which allowed me to size it properly for reconstruction.
I cut out a plate compartment shaped piece and bolted it to the bumper. Then two larger pieces to fill the fog light holes and cut areas, which were then taped down. Then the sides were taped with thin electrical tape to join it all together.
It was all very crude as any imperfections could be mended afterwards.
I sanded down the bumper on areas were the glass fibre and resin would bond to and then carefully waxed all the exposed ply on the inside of the bumper. You want only the ply mould you've made to release. I used wax over release paint as it could be manipulated a lot more easily to cover only the ply.
Then painted the resin over everything and laid 2 layers of ultrathin glass fibre weave which could be shaped into every corner and edge. On top of that I laid a single layer of GF matt. The cardboard ply came off easily and showed how well the GF had taken the shape it needed.
The detailed shot is to show you the sort of quality it had before bodyfilling. Good but basic shape, with plenty of imperfections.
Then I simply bodyfillered all the gaps and corrected any form and sanded. I probably spent about 7 hours of filling and sanding, spread over a few days. The corners I shaped with my fingers and then sanded. Sanded
After sanding I sanded and primed then painted.
I cut the plate light holes and made a little bracket to hold some LEDs, and I also moulded the original bolts in the ply plate piece into the glass fibre so I could mount the number plate. I didn't like the little hooks.
This is the final results, at a track day!