I have an apron of sorts, clipped to the front of my workbench. If I remember, I drape it over my thighs to catch parts. Two problems- I often forget to replace it on thighs if I get up suddenly to grab something out of reach for bench, and parts bounce off of it and get to floor occasionally even if it is in place.
I have been thinking of building a little tray hinged to front of bench, flat bottom covered with thin foam. Have not set it up yet, so don't know if it will work better, but I hope it would eliminate small parts bouncing off and ending up on floor. Amazing how much speed and kinetic energy parts pick up falling just from bench top to top of thighs!