The REAL Challenge. (K'NEX) Answered
Okay. This is the only thing I think is impossible with K'NEX. An H&K GMG. Yeah.
@Range of OVER 10 feet. Okay, whatever. As long as it shoots.
@Must use true grenades, they must explode. OR, you could have it sling balls of K'NEX. Or K'NEX balls.
@Must look like one.
@Must have a tripod.
That's about it.