when i did mine i used MEK, since i had that lying around and no other good use for it. Acetone also works.
you need to make sure your plastic really is abs. i purchased a sheet of it from a local plastic supply store, 2'x4'x1/8" i used about 1 square foot of this material, maybe a bit more.
the smaller the pieces of abs the better, i cut mine into half inch square chunks. really the ideal size is shavings, but i didnt have the time or tools to achieve that. i put the pieces into a jar, and filled it with some MEK. didnt really measure, i just used quite a bit, about 1/4 of the jar. you can always let it evaporate out later. then i let it sit for a few days, came back and found that most of the plastic had clumped to the bottom. i got a wooden chopstick and mixed it around, and did this about every half hour for an entire day. it finally became a nice, but very runny liquid. i then let alot of the MEK evaporate by leaving the lid off for a while. then closing it and shaking, and stirring and repeat. i should have used less MEK and been more patient, but it was my first time.
i went to walmart and found PE containers for stuff like dressings and condiments. they are clear and have a little cap. i poured my mix in there and then used that to squirt my desired amount in the desired place.