Tube glue has its uses, but liquid styrene cement is much neater and more efficient. Apply it sparingly with a fine brush: Join two pieces, load the brush with a minimal amount of cement, and merely touch the join. Capillary action will pull the cement out of the brush and into the join, where it will melt and fuse the plastic mating surfaces. Unlike the old-fashioned tube glue, no blobs, no strings — and it makes a strong bond between plastic pieces. Better yet, if you realize you have glued the wrong two things together, often you can apply a little more liquid cement and part the pieces.