I knew about this very effective thing in some cases.
How to make such effective liquid plastic at home
At this point, however, many are surely wondering "But, how to make effective liquid plastic at home?". First of all it is very important to clarify that we are talking about a plastic...
Exactly! the hardest part in this is creating a design of the piece to be made.
There are some sites where there are already templates to print... try seeing if here: https://www.yeggi.com/ you can find something by entering the make and model of your rc.
a nice 3D printer and print these broken plastics would be handy in these cases. Unfortunately, I have never had one of these printers but it will be my next purchase.