I am assuming this is a weekend retreat, not just a day gathering. If so, I'd bring:
base cardstock
variety of print and solid paper
trimmer
scissors
adhesive (ATG gun, Fabri-Tac, foam dots and maybe my Xyron X)
black & brown Memento ink pads (for Copics)
Copic markers
Scor-Pal (or Scor-Buddy, or bone folder)
ribbon to match paper
embellishments to match paper
stamps
other ink (if I want a color other than my black & brown Memento)
butterfly punch
oval & scallop oval punches
Stickles (takes a LONG time to dry, so only for an overnight retreat)
glitter & embossing powder & heat gun (only if I wanted to get down and dirty)
Big Shot (plus plates & pad)
2 or 3 embossing folders
2-3 different die
Chocolate & soda pop (retreat must-haves!)
But then, I always tend to overpack for retreats.
