There is a very cheap, stable way to create lasting bends in flexible
tubing (Neoprene or natural rubber).  A stiff wire (I usually use
scraps of 12 or 14 gage copper wire) is wound around a wooden dowel
the diameter (or just slightly larger) of the tubing.

Slide the tubing through a small 1-inch section of this spiral and
then slide stretch the spiral along the length of the tubing for,
say, two to three inches and then gently bend into the shape.

In my work with robotics we use this trick for routing pneumatic hoses
all the time (It will even hold a 180 degree bend).  Longer spirals
wound around the tube can be very useful for complex bends, i.e.,
making 'S' bends in two directions.

Ted Konetski