I've been playing a fair bit of Mass Effect and the M-37 Falcon... lots of fun. So, naturally, I made one. I made it a shotgun rather than a grenade launcher because, let's face it, K'nex grenades are utterly useless. It's still fun as hell to shoot. As you can probably tell from the picture, I made a generic but very effective turret design, and threw pieces at it until it looked sort of like a Falcon. No, it's not perfect, but it's a good middle ground between aesthetics and function. It's nearly a metre long and weighs 3.5kg ( about 8 lbs).