This was a concept marker (non-prototype) submitted to the 2009 FASOR design contest held on pbnation. In accordance with the contest, this marker was created to use an air-forward piston with a spring to return it. The unique features about this marker include the trapdoor-style poppet valve, and the body arrangement which converts the traditional stacked-tube arrangement into a variation that hides the upper bore behind the feedneck itself. This makes the body appear regular-sized from the side, but when viewed from the front or back it would appear to be a very slim single-bore marker.
Internals:
Make no mistake, this is only a concept marker at this time. I designed it in a CAD environment with much of the peripherals in place (air routing, frame features, light cosmetic milling, etc) but the firing valve is still very experimental.
The underlying theory is that a hatch-like trapdoor would separate the top from bottom bores and have a hinged pivot located behind it. When the ram piston moves forward, a solid face knocks against a lever attached to the hatch, pushing against the pivot and popping the valve open to deliver an air burst. When the ram retracts, a torsion spring (or similar) is used to collapse the hatch to the sealed position.
The rest of the marker is just a generic design I put forth to create a complete model. It includes amongst other things; reasonably ergonomic frame shape, rear-mounted operation buttons with display LED, internal hoses for air supply, miniature three-way normally-closed solenoid mounted in the frame, lateral circuit board located in back, concealed frame screws, standard 45-style grips, and a non-adjustable feedneck (sorry!). The air supply hoses use a milled manifold component to fork off for various destinations (solenoid; air chamber upper tube). Overall it's an interesting quickie design project and turned out pretty nice in the end.
Solid Media:
My original submission to the design contest can be downloaded here: Hatchmarker.zip
The file contains various SolidWorks files, including SLDPRT parts and SLDASM assemblies. A master "Hatch Assembly" SLDASM file will open the entire marker for viewing, however you will need to temporarily delete the hoses in order to execute a section view (the hose models interfere with the section view).
The models were created in Inventor then converted to be useable with SolidWorks; hence the imported geometry.