Too much, but I'm trying to cut back. Projects are kept in a Ziploc big bag, and I try to keep thread in there. Basic sewing supplies are kept in an over the arm of the couch holder (pin cushion, scissors, seam ripper, white marking pencil, needles), so I can grab and go. Rotary cutter and mat fit in the sewing machine case. The fabric/project bags often do too. I don't usually take an iron because someone else almost always has one. Water to drink and a snack, if all day, something to share. The rest depends on what I'm working on. If more is needed, I also have a rolling cart like those from Staples for moving files, which stays in my car until needed. Some people bring stuff in a foldup little red fabric wagon designed for camping.