Are you planing to build a custom Verp for Kal? Ram Zerimar/Ray Ramirez built the archtype for verps, it's what Kren Traviss used as her inspiration for the gun. Of course, Kal's is custom so I'm sure it's not the exact same as Ram's but, Ram's would give a good foundation for the direction to go. Several members at Mercs have built them as well basically use plywood and PVC pipe.