I use MEK quite a bit, it will melt styrene...any styrene so be careful where you splash it. And it's nasty to the human body, use max ventilation. If you use a plastic brush, it'll melt, if you get it on your hands, it'll dry your skin out and make it crack like Forty Rod said above. I'm positive it's not good to inhale either. I had a gallon can of it but I transfer about a pint at a time into a metal can, the gallon can is almost empty but I've had it for several years.
Doesn't take too long to bond for handling but it does take maybe 15-45 minutes for the joint to be solid enough that it won't move on you. I usually tack 2 pieces together then run the brush down the joint once I get them positioned correctly.
I can find MEK easier than modeling glue!!!
