What I try to have in my portable workshop "kit:"
Sticky notes. Lots of sticky notes, all different colors and sizes. I always have more than I think we'll need… And sometimes we run out. Estimate how many you'll need, and double that number.
Pasteboard. At least 15 sheets.
A roll of butcher paper. At least 2 feet wide.
Blu-tack. For sticking up the poster board and butcher paper.
Pens, markers and pencils. Lots of pens, markers and pencils. Have two packs of each, and add more if you have more participants.
A stopwatch. In case the one on my iPhone fails us (or I need the phone for audio or video recording or photography).
Scissors. To cut the butcher paper. Have a pair for each "team" (if you are having break-out sessions).
Candy. To help keep the energy level up.
Bottled water. For me and participants, to help keep people focused and hydrated (duh).
The schedule of activities/agenda. One for each team.
Play-doh and LEGOS. For the creative exercises and for "idle hands" to play with (helps get people in the right mindset).