This radio receiver style box is ideally suited for that RC related project. the moulding has openings for male headers for connection to servos or to a receiver. Of course it can also be used for many other projects especially where access is required to the PCB such as small presets, teminal blocks etc..
The dimensions in the title are the external 55x36x20mm, and internal 51.5Lx32.4Wx14H.
Note the base is intended to be glued into position on final assembly.