My usual session rucksack:

• 6 plastic recorders in a Sonic the Hedgehog game pouch
  
• metal G clarinet in a souvenir whisky tin which also has:
  
  • folding stand
    
  • spare reeds
    
  • screwdriver
    
  • craft knife for scraping reeds
    
  • medical specimen bottle full of gin to keep the currently-used reed in
  
  
• two Transylvanian drone whistles
  
• a larger flute-thing (either tenor recorder or transverse flute)
  
• maybe a couple of REALLY LOUD wooden recorders in a semi-hard Logitech keyboard case
  
• 3 transverse ocarinas in padded pouches
  
• chalumeau in C in a padded case with a medical specimen bottle full of gin to keep the currently-used reed in
  
• washboard
  
• vintage sparkplug tin holding 10 thimbles
  
• thimble holder
  
• set of table castanets or a guinea pig guiro
  
• roll of plumber's PTFE tape
  
• silk pull-throughs
  
• table clamp if I'm bringing a bass or greatbass recorder
  
• book or CD player for the bus ride there and back