After Market Fiber Glass Parts
Once I started working on it, one by one I kept finding new cracks. More and more, they are everywhere. These bumpers needed to be thrown away. This being a used car lot car, I had to do what they want me to do, even when it is crap work. So I used fiber glass resin to fill all the cracks and this turned out to be a bigger job then I expected. Next time I'll look closer, do a better inspection before bidding a job.
These after market bumpers were secured with 4 screws each. They were flimsy just hanging there. I can only imagine what happened when this car was on the freeway or hit a bump.
When installing an after market bumper that has no holes or attachment points on it, the best way to secure it is going to be matching the attachment points on the original bumper. Drill holes in the same places. Install any brackets that were on the OEM bumper onto the aftermarket one. It will need all the support it can get. I would even go further if you want it to stay on permanently and last longer then a week.
Once all the brackets and screws are in, see if the bumper is still flimsy in some spots. Since this bumper is shaped differently than the original, you may need to fabricate some extra brackets to secure the areas that are not supported.