Here are some cracks in plastic
for the inside of the door panel, today, id use a piece of tin, and span the crack, using probably weldwood dap, properly applied onto the plastic properly prepped. I should say that what I did in the beginning was do the plastic welding using the soldering gun on a hidden crack like that. but later in my refurb i came to realize that extreme bonding and the tin strips worked even better.
On the door handle release bezel, i rebuilt those from the back, carefully, using a soldering gun and black abs pipe. all i aimed for was making it strong, giving it backing, so the screws would actually hold the bezel rather than just screw through the big hole. SEMlandau black works great on those, and the metal door release handles. for the handles i drilled out the rivets, and re-riveted using a basic mastercraft canadian tire rivetgun.
for the last one, the dash, same deal, i used abs plastic to build up the back in a way that strengthens but still allows the panel to seat properly in position.
in my case the pa els were all painted with several colours.....so i repaired and the. coated with landau black. you couldnt tell it wasnt factory unless u were a major afficianado, but there were no switch decal/icons on the panels after i dusted them with landau black.
i would NOT paint the panels unless you absolutely had to.