Q: What type of glue do you use?
A: The glue I use is an solvent/paint stripper. It actually melts the plastic bricks together to make a permanent bond. I do not recommend anyone attempting to use it at home since it is not the healthiest stuff, and requires a good ventilation system.
If you want to glue something together that your child has created, I recommend Elmers white glue, since it is non-toxic and can be dissolved in water if you decide later that you want to be able to reuse the bricks!