Ok, I said I will post how to DIY plastic part. And I will show you my method here. However, the DIY part will not put on my RC10, because I have different idea about fitting the belt.
The procedure is very simple, as long as you have such special glue. This example is not sucsses on its back side, I know you can do better then I did. I personally feel it has simular strength vs. to original plastic part.
This is the plastic part I want to reproduce, because I hate that it got a cut.

By doing this, I need to have original part to copy of course.
You have to prepare this glue. I'm sorry it was wrote in Japanese. And don't ask me what is it, I don't understand Japanese as well.
The glue contains a bottle powder & a bottle of liquid. If you mix them together, it will be solidify in 5 minutes.
It also contains two pices silicon inside. And we need to create mold by using it.
Just put the silicons into 80 degree hot water, it will become very soft. Maybe that is why my wife don't like me to have a bath.
Now, we can make the mold now~
It is time to make the part~
Scatter some powder in, this is very important procedure to prevent bubble.
Add some liquid~
Add some mixed material which catches by the needle. This is very unique method created by the glue maker. I like it!

I'm sorry I can't take photo about how to use the needle to catch the material. Since I have to finish it as soon as I can. It dries cray fast!
Done~ It is a little bit ugly. Since I can't take photos & done this well at the same time.
After 5 minutes, the baby is ready to leave mom.
Believe what you see. It looks very beautiful! Even the "MIP" word.
Trim the edge~
Do it again for another side.
Done. I did very bad job for the back side. However, this is only an example. I don't need the part for my RC10. Because I have better way to fit the belt well.
