well i started with this..
hot glued it into this
then tested the fit like this
sweet pic of the inside
finished with snaps
with added bottom (note extra snap)
note:the fabric inside is crushed panne - my all time fav for hacky sacks
Duck Tape - (DUH) i prefer an off brand not duck brand (Scotch in this case worked awesome)
Fabric - any thing that is preferably soft and light so it doesn't add to much to the case (i recommend crushed panne)
Hot Glue Gun
Snaps - i used a kit from Dritz size 16 snaps (or 7/16")
thats it! just make a sheet of tape, line it, wrap it, snap it, and go!