The Arm Tubes are constructed from 4" thick walled PVC pipe.
There are two straight sections and one 45 degree section for
each arm. The concept is to allow for a bit of bend in the
bottom's elbow, some rotation in the shoulder, and some wiggle room
inside the tube for the entire arm. By doing these things, we
prevent the bottom's arm muscles from cramping. In practice, we
have found it quite frustrating to have arm movement, but still have no
chance of escape.
Note that the short straight section of each arm tube
is not cemented to the
angled section. This is because some folks would not be able to insert
their arms if the parts were rigidly connected. In the image
above, one of the tubes is placed upside down so you can see the holes
that are used to secure the tube to the threaded rod. Several
holes have been drilled, to provide for adjustability.
the images below, you can see how the tubes are mounted to the table.
A single table strap is used around each 45 degree section and
the ends are supported by the threaded rod. A small hole has been
drilled in the ends of each of the two threated rods so that a padlock
can be used to prevent the tubes from being lifted off the supports.