Here's a quick write up of how I fixed my Vert FC's notoriously brittle s4 plastic. This also worked on my friend's old coupe also.

Step 1:
First attain broken FC s4 plastics.

Step 2:
Go to the hobby and craft store and buy plastic cement, this pretty much melts the plastic so it will fuse back together.

Step 3:
Apply generous amounts of the plastic cement to the broken plastic contacts (both sides) and hold firmly together for 30 seconds or so. You can also use small plastic clamps like I did on some bigger pieces.

Step 4:
Set the plastics down somewhere to set up and dry then put em back in the car.

This whole process took about 3 hours start to finish but I ate somewhere in the middle and worked at my own pace so it can be done quicker. But this is so you don't have to buy S5 plastics like a loser. Be a winner and just melt your stuff back together like I did, you'll be happy you only paid 4 bucks versus 140 for new plastic. Try it and see how it works for you, it worked for me great!

 

Some more photos.