Pictured is an IFP tool I made for myself - ones I sold on ebay tended to appear more refined.
In the works is a java applet that illustrates the TALAS system in action - a simple enough mechanism that is far from complex: Best described as clever and finiky. Initial Charles' Law calculations using empirical volume measurements and pressures indicate the system is only marginally linear under a narrow band of ideal STP. An idea is brewing for an infinitely adjustable TALAS type system that offers better linearity with less finikyness.