SLOPMOD
SLOPMOD: based on the Miltary term SOPMOD. A 'slopmod': is a one of a kind hand-made or modified air rifle or pistol that includes tactical elements or styling after modification--SLOPMOD. (2009 NightOpsTech)
What used to be called a "Custom" air rifle, if done by hand, at home could be now called a "SLOPMOD". (2009 NightOpsTech)