>>8101934VERY little.
I recommend getting Tamiya Extra Thin Cement Glue. It's a VERY thin glue that fuses plastics together. It dries quick, it's very thin and watery, cheap, and lasts a long time, and works very well on most model kit plastic. You can add a little dab into cracks and it will quickly fill them and fuse the plastic from the outside.
This stuff is GOOD SHIT for what it is.