I didn't. That's the texture of the horrible Bondo job showing through.
Also, picture time!
Controls are in, but the main stick is loose and doens't center properly. I think I've mostly fixed it now. I screwed up the switch hole; too close to the d-pad. I'm not going to bother re-bondoing it. I did however add some touch-up paint. I mounted the power switches as well, but I still have to put in the hole for the headphone jack. Power and dock ports will go on the back. I tried cutting a cart slot hole and immediately realized it wasn't going to work, so I dremeled the cart slot area off the original YAP64 case and used that instead. I tried a new technique- it's tacked in place with hot glue then liquid ABS is added to actually hold it. I think I have to cut a new hole for the wires as it is right where the cart slot will be.