Cut out two circles of solid wood 6-3/4″ in diameter, for the top and bottom.
Find the centre of the bottom and the top and from that centre make a circle with a 2 3/4″ radius. This circle will act as the centre for the bars.
Mark a bar centre every 30º on the circle. (If you do not have a 60/30º set square, use a protractor, to measure the 30º). Drill 1/2″ holes, 1/4″ deep at all the bar locations.
For the locking bar, drill straight through the bottom and in 5/8″ on the top.
For the slip-out bars, drill straight through the two holes in the bottom.
Fit the bottom to the base with a 1″ machine bolt, countersunk. Tighten the nut so that the bottom will turn freely but snug. Peen (flatten) the end of the bolt so that the nut will never loosen. Plug the bottom and base to hide bolt.
Drill through the locking bar hole into the base 1/2″ deep.
Cut the dowels to the length shown in the materials list.
Assemble the jailhouse without glue to make sure everything fits together as it should.
The slip-out bars will have to be tapered slightly at the bottom so that they will swing out past the top and be released when they are turned and dropped into the locking-bar hole.
When you are satisfied that the puzzle works well, glue six (6) of the twelve (12) bars at the top and bottom. By leaving the others without glue it makes it more difficult to find the locking-bar and the slip-out bars.