A cheap airsoft grenade launcher with ESB EE3 inspiration. This currently represents about two minutes work.
I plan to cover the lower rail with wood, drill some MPP-style holes in the front and perhaps add some piston halves to the flat area in front of the exposed part of the chamber. I'll then need to learn how to weather it.
I like it so far! I would also try to camouflage the top rail as well. That's one of the things that will scream "Modern real world gun!".