The holes in the base and in the upper plate are 0,25mm bigger than the noses of the brace. It should be big enough so that you can stick the socket together. Maybe you have to clean the edges of the first layer. The Viper has to be glued together and also onto the socket. The whole model was printed with a 0,4mm nozzle and 0,2mm layer height with a 1:1 scale. If you are using slic3r try to disable the "thin wall detection" option. Especially the sidewalls of the intake at the bottom of the Viper and also the emblem on the base came out much cleaner with the option disabled.