You can always use the bungie cord in the tube setup to be able to fold the tubes. The new style tents use this method on thier flexible rods so that the tent`s poles can be folded up. Put the bungie cords under a bit of stress so that the tubes tend to want to stay together. You won`t need very much of an interlock and you can set the length of the rods after you have them assembled for the first time. Make sure that the splits have nice radiused edges so that the bungie cords don`t get cut.