Polyester body filler is a more generic term for the brand name product bondo.

If you use an existing model of your suit and chop it up in small enough pieces to print on the bed, you will not have particularly large gaps if done properly. Meshmixer has a "plane cut" feature that performs nicely for this requirement. The segments are cut in such a way that there are zero gaps when assembled. CA glues, especially quality brand name versions will bond PLA quite well.