I used Mr Surfacer 500 first just to glue everything in place (on top of the CA glue) then I’ve been using perfect plastic putty. I’ve found that it isn’t perfect - probably because I’m using fairly flexible sanding sticks I’ve found that I’m still left with a “dent” where the putty was even if I sand carefully. I assume this is because the plastic is much harder than the putty. I’m going to try again with Mr Surfacer 500 as it does get very hard but sands well. Would appreciate any tips though!