YouTube channel Factory Manager made a cardboard AWM which can fire airsoft bullets and eject the casing. It's rather impressive and shows the ingenuity of the PUBG community.
If you're interested in trying this for yourself, the video goes step by step on how to complete the weapon. It's seems a bit advanced, but maybe this is right up your alley.
The YouTube channel seems based out of South Korea so most of the comments are from South Korea. Best of luck trying out to make this masterpiece.
PUBG is not known for creative masterpieces like Overwatch's workshop, but that doesn't mean the community is a bore. They have crafty cheaters, over-achieving dreamers, or vindictive gamers. All of which make the PUBG experience special. So go ahead and work on your cardboard sniper rifle, post on the forums about some obnoxious cheaters and let PUBG Corp know about your frustrations. You're what makes PUBG different.