i have on-the-go trays...
its glasses cases ^^
I have one to put my glass bowl in, one to put my weed sacks, for them to be all together and not falling anywhere in my backpack, and one to roll and put my papes and cissors
its long so when you roll a joint or a blunt and some of the bud falls it falls in it.
and btw i almost always roll joints in parks or anywhere, never at home