No fancy tools necessary, no expensive stuff either... Pick up your favorite drink in a plastic bottle, a length (about 3') of 3/16" vinyl tubing, a 1/4" drill bit, the tiniest drill bit you have (I had a 1/16"), and some super glue {see Picture 1}.
Drill a 1/4" hole in the lid, and then the 1/16" hole adjacent to it. The 1/4" hole is where we'll be inserting the tubing, and the 1/16" is nothing more than a vent {see Picture 2).
Insert your tubing a few inches into the catch bottle {see Picture 3}.
Glue the tubing to the lid {see Picture 4}.
Congratulations! 10 minutes of your time (not including drinking the drink) and you're the proud new owner of a brake fluid catch can {see Picture 5}. Slip the tubing over the nipple of the bleed screw when you bleed the brakes, and follow your normal bleeding procedure. An added benefit to using this catch can, is that this will also allow you to see if there is in fact any air in the lines. When there are no more bubbles, or dark fluid (easy to watch for) you know you're done, and you've got a clean floor to show for your effort!
Tech article by Jason Rodgers (Gummi Bear)