Step 1: Cut a backing board to which you will glue the tubes
Step 2: Mix some wood glue and water about 1:1 ratio
Step 3: Soak the tubes in the glue mixture
Remove the glue soaked tube from the cup and stand it on end on the board you are using for a backing, the board which you have coated with streaks of glue.
Step 5: Drill mounting holes
Step 6: Mount
And you are done. Congrats! Cheap, quick, and easy out of junk you already had. You could do something like this using metal or pvc pipe, or baby food jars (screw the lids to the board), but this is cheaper than buying plastic pipe and such.