Products that used to be called "microweld" or "Scaleweld" depending on what part of the world you are from, along with the liquid testors cement with the brush in the bottle, all use a slight variant on Methalyene Chloride, which will "weld" together acylics, polystyrene (lego or plastic Warhammer guys) in a snap, as well as most ABS types of plastics. Plastruct sells the stuff in a paint thinner sized can, which will last a LONG time, as long as you keep it sealed up tight.
This stuff is TOXIC. The fumes are toxic. Drinking it will kill you. Use plenty of ventilation, especially with acrylics, plexiglas, etc. and DONT drink over crushed ice. Plastic supply houses will sell it in plain brown bottles with a black cap, along with a syringe to apply it, and it works best by capillary action along seams. Letting it bead up on a flat piece of styrene will cause the styrene to warp, melt, and may eat right thru it, so it can also be used for "distressing" ships.
The other thing to watch out for is that it evaporates QUICK! Leave the top off a small bottle of testors, and next morning, you got an empty bottle, and maybe a headache.
For my buck, the best Cyanoacrylate out there is ZapaGap CA+ in the green bottle, and for heavy duty stuff Devcon 2 ton epoxy. Micromark in NJ is the best source of all that stuff, and they have awesome customer service!