Old stuff...
If you haven't been over to Vintage Rex (Marker Museum) you should really take the time to visit. Maybe you have to be an old guy like me to appreciate some of the paintball history displayed there.
It's true all paintball guns are nearly identical; a trigger, a barrel, a body, a grip, etc. But every now and then something comes along that makes you go, "What?"
This is actually a conversion kit. I'm not sure what it's converting to or why someone would want to add 10 pounds to the already behmouth PMI-III (VM-68) that's buried in the middle of this thing. It's called the Bullpup Conversion Kit and only a few were actually made by Pneumatic Ordinance in 1995. (pic and info courtesy of Vintage Rex)