EDIT: Previous thread here viewtopic.php?f=7&t=1796
The wooden frame is local sized lumber bolted together to duplicate a sheet of plywood and allows the steel wrist latches to be mounted at waist level (or anywhere matching holes are drilled). The 3 center boards are covered with a blanket when the black chest and torso straps are used. Otherwise, an oriental bed set covers the frame nicely and makes for a comfortable bed.
The steel plates were purchased prior to making latching with the sliding bolts but were difficult to shape... After only 4 years, the 1 1/4 inch slit for the restraint loop was finally hand-filed to function. Starting with a string of closely spaced drilled holes, a small file set was used to cut and shape the slit. The black sliding bar was purchased locally with the oval slits already formed. These latches are sturdy with no flex or give.
This image shows the timer, pneumatic valves, air tank, wiring, battery, and switch.
The timer is started and shut off using the wired remote power switch (white wire). When powered on, the timer waits 1 minute before powering the solenoids through a MOSFET and starting a 1 hour count down. After reaching 0, it powers off the solenoids and continues to count zero until power is gone. This uses an arduino ardweeny, an led display driver ic, and 2 led 4 digit displays. The 12V battery powers the timer and solenoids. The timer draws 200 to 300 mA depending upon how many segments are lit.
With this iteration, metric air lines are coupled to my original valves with a needle-valve on the valve output line at the "T" fitting. The needle valve controls air flow to the latches and slows piston speed down to something reasonable. Quick release air couplers allow the orange air lines going to each latch to be easily disconnected for storage. The supply air tank is from an international suspension air bag company (fire & stone) purchased for its reasonable price ($45) and low capacity (1/4 gallon, ~1 ltr). This tank may be ordered from EU, AU, and US online retailers. A standard upright bicycle pump can fill it to top pressure quietly and quickly which allows 1 to 2 latch cycles.
The timer circuit close up. Neither pretty nor nicely enclosed, yet it is functional. Since the battery, wood, and most of the bolts will be recycled soon due to a pending life event, this is good enough for now.
A pal of mine has done a lot of stuff like this, though in the partnered bondage situation and for his website 
